Two-camera triangulation scanner with detachable coupling mechanism

ABSTRACT

A three-dimensional ( 3 D) scanner having two cameras and a projector is detachably coupled to a device selected from the group consisting of: an articulated arm coordinate measuring machine, a camera assembly, a six degree-of-freedom (six-DOF) tracker target assembly, and a six-DOF light point target assembly.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/152,266 filed on Apr. 24, 2015, U.S. ProvisionalPatent Application No. 62/152,286, filed on Apr. 24, 2015, U.S.Provisional Patent Application No. 62/152,280, filed on Apr. 24, 2015,U.S. Provisional Patent Application No. 62/152,272, filed on Apr. 24,2015, and U.S. Provisional Patent Application No. 62/152,294, filed onApr. 24, 2015, the entire contents all of which are incorporated hereinby reference.

FIELD OF THE INVENTION

The present disclosure relates to a coordinate measuring machine, andmore particularly to a portable articulated arm coordinate measuringmachine (AACMM) having a detachable accessory device.

BACKGROUND OF THE INVENTION

AACMMs have found widespread use in the manufacturing of parts wherethere is a need to rapidly and accurately verify the dimensions of thepart during various stages of the manufacturing (e.g., machining) of thepart. Portable AACMMs represent a vast improvement over known stationaryor fixed, cost-intensive and relatively difficult to use measurementinstallations, particularly in the amount of time it takes to performdimensional measurements of relatively complex parts. Typically, a userof a portable AACMM simply guides a probe along the surface of the partor object to be measured. The measurement data are then recorded andprovided to the user. In some cases, the data are provided to the userin visual form, for example, three-dimensional (3-D) form on a computerscreen. In other cases, the data are provided to the user in numericform, for example when measuring the diameter of a hole, the text“Diameter=1.0034” is displayed on a computer screen.

Measurements by an AACMM of the three-dimensional (3D) physicalcharacteristics of surfaces of objects may be carried out with contactand non-contact probes for a variety of reasons, including partinspection, rapid prototyping, comparison of the actual part to a CADmodel of the part, reverse engineering, 3D modeling, etc. Most often,non-contact devices use triangulation-based techniques to process theraw captured data to obtain 3D coordinates of surface points.

One type of triangulation-based, non-contact device is a laser lineprobe (LLP), which includes a projector and a camera. The projectorincludes a light source that emits a light, typically as a line. Thus,the LLP is also known as a line scanner. The emitted light may be laserlight, partially coherent light, or incoherent light. The cameraincludes a camera-type imaging device, such as a charge-coupled device(CCD) or CMOS photosensitive array. The camera captures the pattern oflight on the object surface, which is processed to determine 3Dcoordinates of an object surface.

Another type of triangulation-based, non-contact device that includes aprojector and a camera is an area scanner, also known as astructured-light scanner. In such a scanner, the projector projects ontoa surface a two-dimensional pattern that is captured by the camera andprocessed to determine 3D coordinates.

An example of a prior art portable AACMM is disclosed in commonlyassigned U.S. Pat. No. 5,402,582 ('582), which is incorporated herein byreference in its entirety. The '582 patent discloses a 3D measuringsystem comprised of a manually-operated AACMM having a support base onone end and a “hard” measurement probe at the other end. Commonlyassigned U.S. Pat. No. 5,611,147 ('147), which is incorporated herein byreference in its entirety, discloses a similar AACMM. In the '147patent, the articulated arm CMM includes a number of features includingan additional rotational axis at the probe end, thereby providing for anarm with either a two-two-two or a two-two-three axis configuration (thelatter case being a seven axis arm).

It is generally known to attach an LLP to the probe end of an AACMM. Theresult is a fully integrated, portable, contact/non-contact measurementdevice. That is, the AACMM having an LLP attached thereto provides forboth contact measurements of an object through use of the hard probe ofthe AACMM and for non-contact measurements of the object through use ofthe LLP's laser and imaging device. More specifically, the combinationAACMM and LLP allows users to quickly inspect or reverse engineercomplex and organic shapes via laser scanning, as well as to captureprismatic elements with the relatively high accuracy that contactmetrology provides.

When combined as such, the AACMM and LLP may have the LLP carry out someor all of the processing of the 3D captured point cloud data using thesignal processing electronics (e.g., computer or processor) within orassociated with (e.g., located apart from) the AACMM. However, the LLPmay have its own signal processing electronics located within the LLP orassociated with the LLP (e.g., a stand-alone computer) to perform signalprocessing. In this case, the LLP may connect with a display device toview the captured data representing the object.

It is known to disconnect an area scanner from an AACMM for handheldoperation. Usually, such handheld operation is limited to capturing aline of light or pattern of light in a single shot. In such handheldoperation, 3D coordinates of surface points over large areas areobtained by registering together multiple 3D images, usually by matchingcommon image features such as edges or holes. With this method, arelatively large object measured in several scans may provide a singlelarge collection of 3D surface coordinates.

A difficulty with this registration method may arise when an objectbeing scanned has relatively few features. In such a case, a flatsurface may be registered in a warped shape. In addition, although it ispossible to use an area scanner removed from an AACMM in a handheldmode, it has not generally been possible to use an LLP in a handheldmode as a collection of single lines. A potential difficulty is that thecollecting of multiple lines may not provide enough information topermit multiple line-scans to be fit together over a two-dimensionsurface area. Consequently, improvements are desired for methods ofusing a handheld LLP or area scanner to obtain a relatively accurate 3Drepresentation over a relatively large area.

While existing line scanners and area scanners are suitable for theirintended purposes, what is needed is a handheld scanner having improvedregistration over relatively large regions. What is further needed isfor such a handheld scanner to be further useable with an AACMM.

SUMMARY OF THE INVENTION

According to one aspect of the invention, a device for measuringthree-dimensional (3D) coordinates of an object surface includes: aprocessor; and a triangulation scanner including a projector, a firstscanner camera, a second scanner camera, and a scanner connector, thescanner connector configured to detachably couple to an arm connector ofan articulated arm coordinate measurement machine (AACMM), the projectorconfigured to project a scanner pattern onto the object surface, theprojector having a projector perspective center and a projector opticalaxis, the first scanner camera configured to form a first image of thescanner pattern and to send a first electrical scanner signal to theprocessor in response, the first scanner camera having a first-cameraperspective center and a first-camera optical axis, the second scannercamera configured to form a second image of the scanner pattern and tosend a second electrical scanner signal to the processor in response,the second camera having a second-camera perspective center and asecond-camera optical axis, the projector perspective center, thefirst-camera perspective center, and the second-camera perspectivecenter being arranged in a triangular pattern on a first plane, thefirst plane not including the projector optical axis, the first-cameraoptical axis, or the second-camera optical axis, wherein the processoris configured to determine the 3D coordinates of the object surfacewhether the triangulation scanner is coupled to or uncoupled from theAACMM, the determining based at least in part on the scanner pattern,the first electrical scanner signal, and the second electrical scannersignal.

According to a further aspect of the invention, a device for measuringthree-dimensional (3D) coordinates of an object surface includes: aprocessor; and a triangulation scanner including a projector, a scannercamera, a detachable handle, and a scanner connector, the projectorconfigured to project a scanner pattern onto the object surface, thescanner camera configured to form an image of the scanner pattern and tosend an electrical scanner signal to the processor in response, thescanner connector configured to detachably couple to a connector of anarticulated arm coordinate measurement machine (AACMM), the processorbeing configured to determine the 3D coordinates of the object surfacewhether the triangulation scanner is coupled to on uncoupled from theAACMM, the determining based at least in part on the scanner pattern andon the electrical scanner signal, wherein the triangulation scanner isconfigured to sit flat on its bottom after removal of the detachablehandle.

These and other advantages and features will become more apparent fromthe following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, exemplary embodiments are shown whichshould not be construed to be limiting regarding the entire scope of thedisclosure, and wherein the elements are numbered alike in severalFIGURES:

FIGS. 1A and 1B are perspective views of a portable articulated armcoordinate measuring machine (AACMM) having embodiments of variousaspects of the present invention;

FIG. 2, including FIGS. 2A-2D taken together, is a block diagram ofelectronics used as part of the AACMM of FIG. 1 in accordance with anembodiment;

FIG. 3, including FIGS. 3A and 3B taken together, is a block diagramdescribing detailed features of the electronic data processing system ofFIG. 2 in accordance with an embodiment;

FIG. 4 is an isometric view of the probe end of the AACMM of FIG. 1;

FIG. 5 is a side view of the probe end of FIG. 4 with the handle beingcoupled thereto;

FIG. 6 is a side view of the probe end of FIG. 4 with the handleattached;

FIG. 7 is an enlarged partial side view of the interface portion of theprobe end of FIG. 6;

FIG. 8 is another enlarged partial side view of the interface portion ofthe probe end of FIG. 5;

FIG. 9 is an isometric view partially in section of the handle of FIG.4;

FIG. 10A is an isometric view of the probe end of the AACMM of FIG. 1with an LLP attached;

FIG. 10B is an isometric view of an end of the AACMM that includes theprobe tip 118 and scanner 500;

FIG. 10C is an isometric view of an end of the AACMM in a partiallydisassembled and rotated position;

FIG. 11A is an isometric view partially in section of the LLP of FIG.10A;

FIG. 11B is an isometric view, partially disassembled, of the LLP ofFIG. 10A;

FIG. 12 is a schematic illustration of the principle of operation of anLLP according to an embodiment;

FIGS. 13A and 13B are schematic illustrations of the principle oftriangulation for a structured light scanner according to twoembodiments;

FIG. 14A is a schematic representation of elements of a six-DOF scanneraccording to an embodiment;

FIG. 14B is an isometric drawing of a laser tracker according to anembodiment;

FIG. 15A shows a camera bar used to measure a tactile probe havingtargets viewable by the camera bar according to an embodiment;

FIG. 15B shows a camera bar used to measure a triangulation area scannerhaving targets viewable by the camera bar according to an embodiment;

FIG. 15C shows a camera bar used to measure a triangulation line scannerhaving targets viewable by the camera bar according to an embodiment;

FIG. 16 is an isometric view of a scanner assembly having an integratedcollection of cameras, the assembly configured to be attached to anarticulated arm CMM or used separately as a handheld scanner accordingto an embodiment;

FIGS. 17A, 17B, and 17C are orthographic, top, and sectional views of aconnector assembly mechanism according to an embodiment;

FIGS. 18A is an isometric view of a detachable camera assemblyconfigured for coupling to a handheld triangulation scanner according toan embodiment;

FIGS. 18B, 18C, 18D are front, side, and side views, respectively, of adetachable camera assembly attached to a handheld triangulation scanneraccording to an embodiment;

FIG. 18E-18K illustrate methods of measuring 3D coordinates according toan embodiment;

FIGS. 19A, 19B, 19C, 19D are isometric, side, side, and front views,respectively, of a detachable six-degree of freedom (DOF) tracker targetassembly coupled to a handheld triangulation scanner;

FIG. 19E is an isometric view of a detachable six-DOF tracker targetassembly configured for coupling to a handheld triangulation scanneraccording to an embodiment;

FIG. 20 is an isometric view of a detachable six-DOF target assemblycoupled to a handheld triangulation scanner; and

FIGS. 21A, 21B, 21C show a triangulation scanner having a removablehandle and an optional attachable accessory, the attachable accessoryconfigured to help determine position and orientation of thetriangulation scanner in relation to an object;

FIG. 22 shows a two-camera triangulation scanner detachably coupled to asix-DOF tracker target assembly;

FIG. 23A illustrates the concept of epipolar constraints; and

FIG. 23B illustrates the concept of epipolar lines for the case of twocameras and one projector placed in a triangular arrangement accordingto an embodiment.

The detailed description explains embodiments of the invention, togetherwith advantages and features, by way of example with reference to thedrawings.

DETAILED DESCRIPTION

FIGS. 1A and 1B illustrate, in perspective, an articulated armcoordinate measuring machine 100 according to various embodiments of thepresent invention, an articulated arm being one type of coordinatemeasuring machine. As shown in FIGS. 1A and 1B, the exemplary AACMM 100may comprise a six or seven axis articulated measurement device having aprobe end 401 that includes a measurement probe housing 102 coupled toan arm portion 104 of the AACMM 100 at one end. The arm portion 104comprises a first arm segment 106 coupled to a second arm segment 108 bya first grouping of bearing cartridges 110 (e.g., two bearingcartridges). A second grouping of bearing cartridges 112 (e.g., twobearing cartridges) couples the second arm segment 108 to themeasurement probe housing 102. A third grouping of bearing cartridges114 (e.g., three bearing cartridges) couples the first arm segment 106to a base 116 located at the other end of the arm portion 104 of theAACMM 100. Each grouping of bearing cartridges 110, 112, 114 providesfor multiple axes of articulated movement. Also, the probe end 401 mayinclude a measurement probe housing 102 that comprises the shaft of theseventh axis portion of the AACMM 100 (e.g., a cartridge containing anencoder system that determines movement of the measurement device, forexample a probe 118, in the seventh axis of the AACMM 100). In thisembodiment, the probe end 401 may rotate about an axis extending throughthe center of measurement probe housing 102. In use of the AACMM 100,the base 116 is typically affixed to a work surface.

Each bearing cartridge within each bearing cartridge grouping 110, 112,114 typically contains an encoder system (e.g., an optical angularencoder system). The encoder system (i.e., transducer) provides anindication of the position of the respective arm segments 106, 108 andcorresponding bearing cartridge groupings 110, 112, 114 that alltogether provide an indication of the position of the probe 118 withrespect to the base 116 (and, thus, the position of the object beingmeasured by the AACMM 100 in a certain frame of reference—for example alocal or global frame of reference). The arm segments 106, 108 may bemade from a suitably rigid material such as but not limited to a carboncomposite material for example. A portable AACMM 100 with six or sevenaxes of articulated movement (i.e., degrees of freedom) providesadvantages in allowing the operator to position the probe 118 in adesired location within a 360° area about the base 116 while providingan arm portion 104 that may be easily handled by the operator. However,it should be appreciated that the illustration of an arm portion 104having two arm segments 106, 108 is for exemplary purposes, and theclaimed invention should not be so limited. An AACMM 100 may have anynumber of arm segments coupled together by bearing cartridges (and,thus, more or less than six or seven axes of articulated movement ordegrees of freedom).

The probe 118 is detachably mounted to the measurement probe housing102, which is connected to bearing cartridge grouping 112. A handle 126is removable with respect to the measurement probe housing 102 by wayof, for example, a quick-connect interface. As discussed in more detailhereinafter with reference to FIG. 10 et seq., the handle 126 may bereplaced or interchanged with another device such as an LLP, which isconfigured to emit a line of laser light to an object and to capture orimage the laser light on a surface of the object with an imaging device(e.g., a camera) that is part of the LLP, to thereby provide fornon-contact measurement of the dimensions of three-dimensional objects.This interchangeable feature and use of an LLP has the advantage inallowing the operator to make both contact and non-contact measurementswith the same AACMM 100. However, it should be understood that the LLPmay be a standalone device, as described in more detail hereinafter.That is, the LLP may be fully functional and operable by itself withoutany type of connection to the AACMM 100 or similar device.

In exemplary embodiments, the probe housing 102 houses a removable probe118, which is a contacting measurement device and may have differenttips 118 that physically contact the object to be measured, including,but not limited to: ball, touch-sensitive, curved and extension typeprobes. In other embodiments, the measurement is performed, for example,by a non-contacting device such as the LLP. In an embodiment, the handle126 is replaced with the LLP using the quick-connect interface. Othertypes of measurement devices may replace the removable handle 126 toprovide additional functionality. Examples of such measurement devicesinclude, but are not limited to, one or more illumination lights, atemperature sensor, a thermal scanner, a bar code scanner, a projector,a paint sprayer, a camera, or the like, for example.

As shown in FIGS. 1A and 1B, the AACMM 100 includes the removable handle126 that provides advantages in allowing accessories or functionality tobe changed without removing the measurement probe housing 102 from thebearing cartridge grouping 112. As discussed in more detail below withrespect to FIG. 2D, the removable handle 126 may also include anelectrical connector that allows electrical power and data to beexchanged with the handle 126 and the corresponding electronics locatedin the probe end 401.

In various embodiments, each grouping of bearing cartridges 110, 112,114 allows the arm portion 104 of the AACMM 100 to move about multipleaxes of rotation. As mentioned, each bearing cartridge grouping 110,112, 114 includes corresponding encoder systems, such as optical angularencoders for example, that are each arranged coaxially with thecorresponding axis of rotation of, e.g., the arm segments 106, 108. Theoptical encoder system detects rotational (swivel) or transverse (hinge)movement of, e.g., each one of the arm segments 106, 108 about thecorresponding axis and transmits a signal to an electronic dataprocessing system within the AACMM 100 as described in more detailhereinafter. Each individual raw encoder count is sent separately to theelectronic data processing system as a signal where it is furtherprocessed into measurement data. No position calculator separate fromthe AACMM 100 itself (e.g., a serial box) is required, as disclosed incommonly assigned U.S. Pat. No. 5,402,582 ('582).

The base 116 may include an attachment device or mounting device 120.The mounting device 120 allows the AACMM 100 to be removably mounted toa desired location, such as an inspection table, a machining center, awall or the floor, for example. In one embodiment, the base 116 includesa handle portion 122 that provides a convenient location for theoperator to hold the base 116 as the AACMM 100 is being moved. In oneembodiment, the base 116 further includes a movable cover portion 124that folds down to reveal a user interface, such as a display screen.

In accordance with an embodiment, the base 116 of the portable AACMM 100contains or houses an electronic circuit having an electronic dataprocessing system that includes two primary components: a baseprocessing system that processes the data from the various encodersystems within the AACMM 100 as well as data representing other armparameters to support three-dimensional positional calculations; and auser interface processing system that includes an on-board operatingsystem, a touch screen display, and resident application software thatallows for relatively complete metrology functions to be implementedwithin the AACMM 100 without the need for connection to an externalcomputer. It should be appreciated that in other embodiments, the AACMM100 may be configured with the user interface processing system arrangedremote or distant from the device, such as on a laptop, a remotecomputer or a portable/mobile computing device (e.g. a cellular phone ora tablet computer).

The electronic data processing system in the base 116 may communicatewith the encoder systems, sensors, and other peripheral hardware locatedaway from the base 116 (e.g., a laser line probe that can be mounted inplace of the removable handle 126 on the AACMM 100). The electronicsthat support these peripheral hardware devices or features may belocated in each of the bearing cartridge groupings 110, 112, 114 locatedwithin the portable AACMM 100.

FIG. 2 is a block diagram of electronics utilized in an AACMM 100 inaccordance with an embodiment. The embodiment shown in FIG. 2A includesan electronic data processing system 210 including a base processorboard 204 for implementing the base processing system, a user interfaceboard 202, a base power board 206 for providing power, a Bluetoothmodule 232, and a base tilt board 208. The user interface board 202includes a computer processor for executing application software toperform user interface, display, and other functions described herein.

As shown in FIG. 2A and FIG. 2B, the electronic data processing system210 is in communication with the aforementioned plurality of encodersystems via one or more arm buses 218. In the embodiment depicted inFIG. 2B and FIG. 2C, each encoder system generates encoder data andincludes: an encoder arm bus interface 214, an encoder digital signalprocessor (DSP) 216, an encoder read head interface 234, and atemperature sensor 212. Other devices, such as strain sensors, may beattached to the arm bus 218.

Also shown in FIG. 2D are probe end electronics 230 that are incommunication with the arm bus 218. The probe end electronics 230include a probe end DSP 228, a temperature sensor 212, a handle/deviceinterface bus 240 that connects with the handle 126 or the LLP 242 viathe quick-connect interface in an embodiment, and a probe interface 226.The quick-connect interface allows access by the handle 126 to the databus, control lines, and power bus used by the LLP 242 and otheraccessories. In an embodiment, the probe end electronics 230 are locatedin the measurement probe housing 102 on the AACMM 100. In an embodiment,the handle 126 may be removed from the quick-connect interface andmeasurement may be performed by the LLP 242 communicating with the probeend electronics 230 of the AACMM 100 via the interface bus 240. In anembodiment, the electronic data processing system 210 is located in thebase 116 of the AACMM 100, the probe end electronics 230 are located inthe measurement probe housing 102 of the AACMM 100, and the encodersystems are located in the bearing cartridge groupings 110, 112, 114.The probe interface 226 may connect with the probe end DSP 228 by anysuitable communications protocol, including commercially-availableproducts from Maxim Integrated Products, Inc. that embody the 1-wire®communications protocol 236.

FIG. 3 is a block diagram describing detailed features of the electronicdata processing system 210 of the AACMM 100 in accordance with anembodiment. In an embodiment, the electronic data processing system 210is located in the base 116 of the AACMM 100 and includes the baseprocessor board 204, the user interface board 202, a base power board206, a Bluetooth module 232, and a base tilt module 208.

In an embodiment shown in FIG. 3A, the base processor board 204 includesthe various functional blocks illustrated therein. For example, a baseprocessor function 302 is utilized to support the collection ofmeasurement data from the AACMM 100 and receives raw arm data (e.g.,encoder system data) via the arm bus 218 and a bus control modulefunction 308. The memory function 304 stores programs and static armconfiguration data. The base processor board 204 also includes anexternal hardware option port function 310 for communicating with anyexternal hardware devices or accessories such as the LLP 242. A realtime clock (RTC) and log 306, a battery pack interface (IF) 316, and adiagnostic port 318 are also included in the functionality in anembodiment of the base processor board 204 depicted in FIG. 3A.

The base processor board 204 also manages all the wired and wirelessdata communication with external (host computer) and internal (displayprocessor 202) devices. The base processor board 204 has the capabilityof communicating with an Ethernet network via an Ethernet function 320(e.g., using a clock synchronization standard such as Institute ofElectrical and Electronics Engineers (“IEEE”) 1588), with a wirelesslocal area network (WLAN) via a LAN function 322, and with Bluetoothmodule 232 via a parallel to serial communications (PSC) function 314.The base processor board 204 also includes a connection to a universalserial bus (USB) device 312.

The base processor board 204 transmits and collects raw measurement data(e.g., encoder system counts, temperature readings) for processing intomeasurement data without the need for any preprocessing, such asdisclosed in the serial box of the aforementioned '582 patent. The baseprocessor 204 sends the processed data to the display processor 328 onthe user interface board 202 via an RS485 interface (IF) 326. In anembodiment, the base processor 204 also sends the raw measurement datato an external computer.

Turning now to the user interface board 202 shown in FIG. 3B, the angleand positional data received by the base processor is utilized byapplications executing on the display processor 328 to provide anautonomous metrology system within the AACMM 100. Applications may beexecuted on the display processor 328 to support functions such as, butnot limited to: measurement of features, guidance and training graphics,remote diagnostics, temperature corrections, control of variousoperational features, connection to various networks, and display ofmeasured objects. Along with the display processor 328 and a liquidcrystal display (LCD) 338 (e.g., a touch screen LCD) user interface, theuser interface board 202 includes several interface options including asecure digital (SD) card interface 330, a memory 332, a USB Hostinterface 334, a diagnostic port 336, a camera port 340, an audio/videointerface 342, a dial-up/cell modem 344 and a global positioning system(GPS) port 346.

The electronic data processing system 210 shown in FIG. 3A may alsoinclude a base power board 206 with an environmental recorder 362 forrecording environmental data. The base power board 206 also providespower to the electronic data processing system 210 using an AC/DCconverter 358 and a battery charger control 360. The base power board206 communicates with the base processor board 204 usinginter-integrated circuit (I2C) serial single ended bus 354 as well asvia a DMA serial peripheral interface (DSPI) 357. The base power board206 is connected to a tilt sensor and radio frequency identification(RFID) module 208 via an input/output (I/O) expansion function 364implemented in the base power board 206.

Though shown as separate components, in other embodiments all or asubset of the components may be physically located in differentlocations and/or functions combined in different manners than that shownin FIG. 3A and FIG. 3B. For example, in one embodiment, the baseprocessor board 204 and the user interface board 202 are combined intoone physical board.

Referring now to FIGS. 4-9, an exemplary embodiment of a probe end 401is illustrated having a measurement probe housing 102 with aquick-connect mechanical and electrical interface that allows removableand interchangeable device 400 to couple with AACMM 100. It should beappreciated that the illustrated embodiment shows a particularconfiguration of a mechanical and electrical interface between the probehousing and the device 400, other interfaces may also be used. In theexemplary embodiment, the device 400 includes an enclosure 402 having ahandle portion 404 that is sized and shaped to be held in an operator'shand, such as in a pistol grip for example. The enclosure 402 is a thinwall structure having a cavity 406 (FIG. 9). The cavity 406 is sized andconfigured to receive a controller 408. The controller 408 may be adigital circuit, having a microprocessor for example, or an analogcircuit. In one embodiment, the controller 408 is in asynchronousbidirectional communication with the electronic data processing system210 (FIGS. 2 and 3). The communication connection between the controller408 and the electronic data processing system 210 may be wired (e.g. viacontroller 420) or may be a direct or indirect wireless connection(e.g., Bluetooth or IEEE 802.11) or a combination of wired and wirelessconnections. In the exemplary embodiment, the enclosure 402 is formed intwo halves 410, 412, such as from an injection molded plastic materialfor example. The halves 410, 412 may be secured together by fasteners,such as screws 414 for example. In other embodiments, the enclosurehalves 410, 412 may be secured together by adhesives or ultrasonicwelding for example.

The handle portion 404 also includes buttons or actuators 416, 418 thatmay be manually activated by the operator. The actuators 416, 418 arecoupled to the controller 408 that transmits a signal to a controller420 within the probe housing 102. In the exemplary embodiments, theactuators 416, 418 perform the functions of actuators 422, 424 locatedon the probe housing 102 opposite the device 400. It should beappreciated that the device 400 may have additional switches, buttons orother actuators that may also be used to control the device 400, theAACMM 100 or vice versa. Also, the device 400 may include indicators,such as LEDs, sound generators, meters, displays or gauges for example.In one embodiment, the device 400 may include a digital voice recorderthat allows for synchronization of verbal comments with a measuredpoint. In yet another embodiment, the device 400 includes a microphonethat allows the operator to record comments or transmit voice activatedcommands to the electronic data processing system 210.

In one embodiment, the handle portion 404 may be configured to be usedwith either operator hand or for a particular hand (e.g. left handed orright handed). The handle portion 404 may also be configured tofacilitate operators with disabilities (e.g. operators with missingfinders or operators with prosthetic arms). Further, the handle portion404 may be removed and the probe housing 102 used by itself whenclearance space is limited. As discussed above, the probe end 401 mayalso comprise the shaft of the seventh axis of AACMM 100. In thisembodiment the device 400 may be arranged to rotate about the AACMMseventh axis.

The probe end 401 includes a mechanical and electrical interface 426having a first connector 429 (FIG. 8) on the device 400 that cooperateswith a second connector 428 on the probe housing 102. The connectors428, 429 may include electrical and mechanical features that allow forcoupling of the device 400 to the probe housing 102. In one embodiment,the interface 426 includes a first surface 430 having a mechanicalcoupler 432 and an electrical connector 434 thereon. The enclosure 402also includes a second surface 436 positioned adjacent to and offsetfrom the first surface 430. In the exemplary embodiment, the secondsurface 436 is a planar surface offset a distance of approximately 0.5inches from the first surface 430. This offset provides a clearance forthe operator's fingers when tightening or loosening a fastener such ascollar 438. The interface 426 provides for a relatively quick and secureelectronic connection between the device 400 and the probe housing 102without the need to align connector pins, and without the need forseparate cables or connectors.

The electrical connector 434 extends from the first surface 430 andincludes one or more connector pins 440 that are electrically coupled inasynchronous bidirectional communication with the electronic dataprocessing system 210 (FIGS. 2 and 3), such as via one or more arm buses218 for example. The bidirectional communication connection may be wired(e.g. via arm bus 218), wireless (e.g. Bluetooth or IEEE 802.11), or acombination of wired and wireless connections. In one embodiment, theelectrical connector 434 is electrically coupled to the controller 420.The controller 420 may be in asynchronous bidirectional communicationwith the electronic data processing system 210 such as via one or morearm buses 218 for example. The electrical connector 434 is positioned toprovide a relatively quick and secure electronic connection withelectrical connector 442 on probe housing 102. The electrical connectors434, 442 connect with each other when the device 400 is attached to theprobe housing 102. The electrical connectors 434, 442 may each comprisea metal encased connector housing that provides shielding fromelectromagnetic interference as well as protecting the connector pinsand assisting with pin alignment during the process of attaching thedevice 400 to the probe housing 102.

The mechanical coupler 432 provides relatively rigid mechanical couplingbetween the device 400 and the probe housing 102 to support relativelyprecise applications in which the location of the device 400 on the endof the arm portion 104 of the AACMM 100 preferably does not shift ormove. Any such movement may typically cause an undesirable degradationin the accuracy of the measurement result. These desired results areachieved using various structural features of the mechanical attachmentconfiguration portion of the quick connect mechanical and electronicinterface of an embodiment of the present invention.

In one embodiment, the mechanical coupler 432 includes a firstprojection 444 positioned on one end 448 (the leading edge or “front” ofthe device 400). The first projection 444 may include a keyed, notchedor ramped interface that forms a lip 446 that extends from the firstprojection 444. The lip 446 is sized to be received in a slot 450defined by a projection 452 extending from the probe housing 102 (FIG.8). It should be appreciated that the first projection 444 and the slot450 along with the collar 438 form a coupler arrangement such that whenthe lip 446 is positioned within the slot 450, the slot 450 may be usedto restrict both the longitudinal and lateral movement of the device 400when attached to the probe housing 102. As will be discussed in moredetail below, the rotation of the collar 438 may be used to secure thelip 446 within the slot 450.

Opposite the first projection 444, the mechanical coupler 432 mayinclude a second projection 454. The second projection 454 may have akeyed, notched-lip or ramped interface surface 456 (FIG. 5). The secondprojection 454 is positioned to engage a fastener associated with theprobe housing 102, such as collar 438 for example. As will be discussedin more detail below, the mechanical coupler 432 includes a raisedsurface projecting from surface 430 that is adjacent to or disposedabout the electrical connector 434 which provides a pivot point for theinterface 426 (FIGS. 7 and 8). This serves as the third of three pointsof mechanical contact between the device 400 and the probe housing 102when the device 400 is attached thereto.

The probe housing 102 includes a collar 438 arranged co-axially on oneend. The collar 438 includes a threaded portion that is movable betweena first position (FIG. 5) and a second position (FIG. 7). By rotatingthe collar 438, the collar 438 may be used to secure or remove thedevice 400 without the need for external tools. Rotation of the collar438 moves the collar 438 along a relatively coarse, square-threadedcylinder 474. The use of such relatively large size, square-thread andcontoured surfaces allows for significant clamping force with minimalrotational torque. The coarse pitch of the threads of the cylinder 474further allows the collar 438 to be tightened or loosened with minimalrotation.

To couple the device 400 to the probe housing 102, the lip 446 isinserted into the slot 450 and the device is pivoted to rotate thesecond projection 454 toward surface 458 as indicated by arrow 464 (FIG.5). The collar 438 is rotated causing the collar 438 to move ortranslate in the direction indicated by arrow 462 into engagement withsurface 456. The movement of the collar 438 against the angled surface456 drives the mechanical coupler 432 against the raised surface 460.This assists in overcoming potential issues with distortion of theinterface or foreign objects on the surface of the interface that couldinterfere with the rigid seating of the device 400 to the probe housing102. The application of force by the collar 438 on the second projection454 causes the mechanical coupler 432 to move forward pressing the lip446 into a seat on the probe housing 102. As the collar 438 continues tobe tightened, the second projection 454 is pressed upward toward theprobe housing 102 applying pressure on a pivot point. This provides asee-saw type arrangement, applying pressure to the second projection454, the lip 446 and the center pivot point to reduce or eliminateshifting or rocking of the device 400. The pivot point presses directlyagainst the bottom on the probe housing 102 while the lip 446 is appliesa downward force on the end of probe housing 102. FIG. 5 includes arrows462, 464 to show the direction of movement of the device 400 and thecollar 438. FIG. 7 includes arrows 466, 468, 470 to show the directionof applied pressure within the interface 426 when the collar 438 istightened. It should be appreciated that the offset distance of thesurface 436 of device 400 provides a gap 472 between the collar 438 andthe surface 436 (FIG. 6). The gap 472 allows the operator to obtain afirmer grip on the collar 438 while reducing the risk of pinchingfingers as the collar 438 is rotated. In one embodiment, the probehousing 102 is of sufficient stiffness to reduce or prevent thedistortion when the collar 438 is tightened.

Embodiments of the interface 426 allow for the proper alignment of themechanical coupler 432 and electrical connector 434 and also protect theelectronics interface from applied stresses that may otherwise arise dueto the clamping action of the collar 438, the lip 446 and the surface456. This provides advantages in reducing or eliminating stress damageto circuit board 476 mounted electrical connectors 434, 442 that mayhave soldered terminals. Also, embodiments provide advantages over knownapproaches in that no tools are required for a user to connect ordisconnect the device 400 from the probe housing 102. This allows theoperator to manually connect and disconnect the device 400 from theprobe housing 102 with relative ease.

Due to the relatively large number of shielded electrical connectionspossible with the interface 426, a relatively large number of functionsmay be shared between the AACMM 100 and the device 400. For example,switches, buttons or other actuators located on the AACMM 100 may beused to control the device 400 or vice versa. Further, commands and datamay be transmitted from electronic data processing system 210 to thedevice 400. In one embodiment, the device 400 is a video camera thattransmits data of a recorded image to be stored in memory on the baseprocessor 204 or displayed on the display 328. In another embodiment thedevice 400 is an image projector that receives data from the electronicdata processing system 210. In addition, temperature sensors located ineither the AACMM 100 or the device 400 may be shared by the other. Itshould be appreciated that embodiments of the present invention provideadvantages in providing a flexible interface that allows a wide varietyof accessory devices 400 to be quickly, easily and reliably coupled tothe AACMM 100. Further, the capability of sharing functions between theAACMM 100 and the device 400 may allow a reduction in size, powerconsumption and complexity of the AACMM 100 by eliminating duplicity.

In one embodiment, the controller 408 may alter the operation orfunctionality of the probe end 401 of the AACMM 100. For example, thecontroller 408 may alter indicator lights on the probe housing 102 toeither emit a different color light, a different intensity of light, orturn on/off at different times when the device 400 is attached versuswhen the probe housing 102 is used by itself. In one embodiment, thedevice 400 includes a range finding sensor (not shown) that measures thedistance to an object. In this embodiment, the controller 408 may changeindicator lights on the probe housing 102 in order to provide anindication to the operator how far away the object is from the probe tip118. In another embodiment, the controller 408 may change the color ofthe indicator lights based on the quality of the image acquired by theLLP 242. This provides advantages in simplifying the requirements ofcontroller 420 and allows for upgraded or increased functionalitythrough the addition of accessory devices.

Referring to FIGS. 10-11, embodiments of the present invention provideadvantages for camera, signal processing, control, and indicatorinterfaces for an scanner 500, which is part of a measurement unit 490.The scanner 500 may refer to the electrical elements LLP 242 asreferenced hereinabove with respect to FIGS. 1-9. The scanner may be anLLP or it may be an area scanner, as explained in more detail hereinbelow. The LLP 500 provides for non-contact measurements of an object,typically in the same frame of reference as that of the hard probe 118of the AACMM 100, as discussed herein above. Further, the calculatedthree-dimensional coordinates of surface points provided by the scanner500 are based on the known principles of triangulation, as explained inmore detail herein below. The scanner 500 may include an enclosure 502with a handle portion 504. The LLP 500 further includes an interface 426on one end that mechanically and electrically couples the scanner 500 tothe probe housing 102 as described hereinabove. The interface 426 allowsthe scanner 500 to be coupled and removed from the AACMM 100 quickly andeasily without requiring additional tools.

Adjacent the interface 426, the enclosure 502 has a portion 506 (FIG.11A) that includes a camera 508 and a projector 510. In the exemplaryembodiment, the projector 510 uses a light source that generates astraight line projected onto an object surface. The light source may bea laser, a superluminescent diode (SLD), an incandescent light, a lightemitting diode (LED), for example. The projected light may be visible orinvisible, but visible light may be more convenient for an operator insome cases. The camera 508 includes a lens and an imaging sensor. Theimaging sensor is a photosensitive array that may be a charge-coupleddevice (CCD) two-dimensional (2D) area sensor or a complementarymetal-oxide-semiconductor (CMOS) 2D area sensor, for example, or it maybe some other type of device. Each imaging sensor may comprise a 2Darray (i.e., rows, columns) of a plurality of light sensing pictureelements (pixels). Each pixel typically contains at least onephotodetector that converts light into an electric charge stored withinthe pixel wells, and read out as a voltage value. Voltage values areconverted into digital values by an analog-to-digital converter (ADC).Typically for a CMOS sensor chip, the ADC is contained within the sensorchip. Typically for a CCD sensor chip, the ADC is included outside thesensor chip on a circuit board.

In an exemplary embodiment, the projector 510 and camera 508 areoriented to enable reflected light to be imaged by the photosensitivearray. In one embodiment, the scanner 500 is offset from the probe tip118 to enable the scanner 500 to be operated without interference fromthe probe tip 118. In other words, the scanner 500 may be operated withthe probe tip 118 in place. Further, it should be appreciated that thescanner 500 is substantially fixed relative to the probe tip 118 so thatforces on the handle portion 504 do not influence the alignment of thescanner 500 relative to the probe tip 118. In one embodiment, thescanner 500 may have an additional actuator (not shown) that allows theoperator to switch between acquiring data from the scanner 500 and theprobe tip 118.

The projector 510 and camera 508 are electrically coupled to acontroller 512 disposed within the enclosure 502. The controller 512 mayinclude one or more microprocessors, digital signal processors, memory,and other types of signal conditioning and/or storage circuits. In anembodiment, due to the large data volume generated by the scanner 500,the controller 512 may be arranged within the handle portion 504. Thecontroller 512 is electrically coupled to the arm buses 218 viaelectrical connector 434. The scanner 500 further includes actuators514, 516 which may be manually activated by the operator to initiateoperation and data capture by the scanner 500.

The marker light source 509 emits a beam of light that intersects thebeam of light from the projector 510. The position at which the twobeams intersect provides an indication to the user of the optimumdistance from the scanner 500 to the object under test. The scanner 500will make good measurements for some distance on either side of theoptimum distance, but the position of intersection of the beams of lightfrom marker light source 509 and the projector 510 provides the userwith a convenient indication of the proper stand-off distance for thescanner 500.

FIG. 10B shows the probe end 401 and scanner 500 attached to the secondgrouping of bearing cartridges 112. This grouping is attached to thesecond arm segment 108, which is a part of the AACMM 100.

FIG. 10C shows the probe end 401 and the scanner 500 in an exploded androtated view that shows the interface 426 that includes scannerconnector 426A and the probe end connector 426C.

FIGS. 11A and 11B show internal elements of the scanner 500 according toan embodiment. FIG. 11A is a partial sectional view that reveals someelectrical components within the handle 504. The electrical componentsinclude connections to actuators (e.g., pushbuttons) 514, 516.Additional electrical components are located above the handle 504 in theenclosure of the scanner 500. In an embodiment, an outer shell 1105,which in an embodiment is made of plastic, is provided for cosmeticappearance and protection.

FIG. 11B is a partial disassembled view of the scanner 500. In anembodiment, elements of camera 508 include a camera assembly 1110 thatincludes a housing 1112, multiple lens elements (not shown) within thehousing 112, and a protective cover window 1114. The camera assembly1110 is held in place by tabs or fingers 1120, which are held tightlyagainst the fingers by the clamp 1122. In an embodiment, the markerlight source 509 includes a housing 1132 and a cover window 1134. Theprojector includes a cover window 1140. The windows 1114, 1134, and 1140lie substantially flush with the exterior surface of the outer shell1105 to facilitate cleaning of the window surfaces. The scanner 500includes a rigid structure having elements that include a front metalpanel 1150, the camera 508, the marker light source 509, the projector510, and the mechanical and electrical interface 426. These elements areheld in together in a rigid and stable assembly. The front metal panel1150 is attached to the interface 426 with screws 1152.

FIG. 12 shows elements of an LLP 4500 that includes a projector 4520 anda camera 4540. The projector 4520 includes a source pattern of light4521 and a projector lens 4522. The source pattern of light includes anilluminated pattern in the form of a line. The projector lens includes aprojector perspective center and a projector optical axis that passesthrough the projector perspective center. In the example of FIG. 12, acentral ray of the beam of light 4524 is aligned with the projectoroptical axis. The camera 4540 includes a camera lens 4542 and aphotosensitive array 4541. The lens has a camera optical axis 4543 thatpasses through a camera lens perspective center 4544. In the exemplarysystem 4500, the projector optical axis, which is aligned to the beam oflight 4524 and the camera lens optical axis 4544, are perpendicular tothe line of light 4523 projected by the source pattern of light 4521. Inother words, the line 4523 is in the direction perpendicular to thepaper in FIG. 12. The line strikes an object surface, which at a firstdistance from the projector is object surface 4510A and at a seconddistance from the projector is object surface 4510B. It is understoodthat at different heights above or below the plane of the paper of FIG.12, the object surface may be at a different distance from theprojector. The line of light intersects surface 4510A (in the plane ofthe paper) in a point 4526, and it intersects the surface 4510B (in theplane of the paper) in a point 4527. For the case of the intersectionpoint 4526, a ray of light travels from the point 4526 through thecamera lens perspective center 4544 to intersect the photosensitivearray 4541 in an image point 4546. For the case of the intersectionpoint 4527, a ray of light travels from the point 4527 through thecamera lens perspective center to intersect the photosensitive array4541 in an image point 4547. By noting the position of the intersectionpoint relative to the position of the camera lens optical axis 4544, thedistance from the projector (and camera) to the object surface can bedetermined using the principles of triangulation. The distance from theprojector to other points on the line of light 4526, that is points onthe line of light that do not lie in the plane of the paper of FIG. 12,may similarly be found.

In an embodiment, the photosensitive array 4541 is aligned to placeeither the array rows or columns in the direction of the reflected laserstripe. In this case, the position of a spot of light along onedirection of the array provides information to determine a distance tothe object, as indicated by the difference in the positions of the spots4546 and 4547 of FIG. 12. The position of the spot of light in theorthogonal direction on the array provides information to determinewhere, along the length of the laser line, the plane of light intersectsthe object.

As used herein, it is understood that the terms column and row refersimply to a first direction along the photosensitive array and a seconddirection perpendicular to the first direction. As such, the terms rowand column as used herein do not necessarily refer to row and columnsaccording to documentation provided by a manufacturer of thephotosensitive array 4541. In the discussion that follows, the rows aretaken to be in the plane of the paper on the surface of thephotosensitive array. The columns are taken to be on the surface of thephotosensitive array and orthogonal to the rows. However it should beappreciated that other arrangements are possible.

As explained herein above, light from a scanner may be projected in aline pattern to collect 3D coordinates over a line. Alternatively, lightfrom a scanner may be projected to cover an area, thereby obtaining 3Dcoordinates over an area on an object surface. In an embodiment, theprojector 508 in FIGS. 10-11 is an area projector rather than a lineprojector. An explanation of triangulation principles for the case ofarea projection is now given with reference to the system 2560 of FIG.13A and the system 4760 of FIG. 13B. Referring first to FIG. 13A, thesystem 2560 includes a projector 2562 and a camera 2564. The projector2562 includes a source pattern of light 2570 lying on a source plane anda projector lens 2572. The projector lens may include several lenselements. The projector lens has a lens perspective center 2575 and aprojector optical axis 2576. The ray of light 2573 travels from a point2571 on the source pattern of light through the lens perspective centeronto the object 2590, which it intercepts at a point 2574.

The camera 2564 includes a camera lens 2582 and a photosensitive array2580. The camera lens 2582 has a lens perspective center 2585 and anoptical axis 2586. A ray of light 2583 travels from the object point2574 through the camera perspective center 2585 and intercepts thephotosensitive array 2580 at point 2581.

The line segment that connects the perspective centers is the baseline2588 in FIG. 13A and the baseline 4788 in FIG. 13B. The length of thebaseline is called the baseline length (2592, 4792). The angle betweenthe projector optical axis and the baseline is the baseline projectorangle (2594, 4794). The angle between the camera optical axis (2583,4786) and the baseline is the baseline camera angle (2596, 4796). If apoint on the source pattern of light (2570, 4771) is known to correspondto a point on the photosensitive array (2581, 4781), then it is possibleusing the baseline length, baseline projector angle, and baseline cameraangle to determine the sides of the triangle connecting the points 2585,2574, and 2575, and hence determine the surface coordinates of points onthe surface of object 2590 relative to the frame of reference of themeasurement system 2560. To do this, the angles of the sides of thesmall triangle between the projector lens 2572 and the source pattern oflight 2570 are found using the known distance between the lens 2572 andplane 2570 and the distance between the point 2571 and the intersectionof the optical axis 2576 with the plane 2570. These small angles areadded or subtracted from the larger angles 2596 and 2594 as appropriateto obtain the desired angles of the triangle. It will be clear to one ofordinary skill in the art that equivalent mathematical methods can beused to find the lengths of the sides of the triangle 2574-2585-2575 orthat other related triangles may be used to obtain the desiredcoordinates of the surface of object 2590.

Referring first to FIG. 13B, the system 4760 is similar to the system2560 of FIG. 13A except that the system 4760 does not include a lens.The system may include a projector 4762 and a camera 4764. In theembodiment illustrated in FIG. 13B, the projector includes a lightsource 4778 and a light modulator 4770. The light source 4778 may be alaser light source since such a light source may remain in focus for along distance using the geometry of FIG. 13B. A ray of light 4773 fromthe light source 4778 strikes the optical modulator 4770 at a point4771. Other rays of light from the light source 4778 strike the opticalmodulator at other positions on the modulator surface. In an embodiment,the optical modulator 4770 changes the power of the emitted light, inmost cases by decreasing the optical power to a degree. In this way, theoptical modulator imparts an optical pattern to the light, referred tohere as the source pattern of light, which is at the surface of theoptical modulator 4770. The optical modulator 4770 may be a DLP or LCOSdevice for example. In some embodiments, the modulator 4770 istransmissive rather than reflective. The light emerging from the opticalmodulator 4770 appears to emerge from a virtual light perspective center4775. The ray of light appears to emerge from the virtual lightperspective center 4775, pass through the point 4771, and travel to thepoint 4774 at the surface of object 4790.

The baseline is the line segment extending from the camera lensperspective center 4785 to the virtual light perspective center 4775. Ingeneral, the method of triangulation involves finding the lengths of thesides of a triangle, for example, the triangle having the vertex points4774, 4785, and 4775. One method for doing this is to find the length ofthe baseline, the angle between the baseline and the camera optical axis4786, and the angle between the baseline and the projector referenceaxis 4776. To find the desired angle, additional smaller angles arefound. For example, the small angle between the camera optical axis 4786and the ray 4783 can be found by solving for the angle of the smalltriangle between the camera lens 4782 and the photosensitive array 4780based on the distance from the lens to the photosensitive array and thedistance of the pixel from the camera optical axis. The angle of thesmall triangle is then added to the angle between the baseline and thecamera optical axis to find the desired angle. Similarly for theprojector, the angle between the projector reference axis 4776 and theray 4773 is found can be found by solving for the angle of the smalltriangle between these two lines based on the known distance of thelight source 4777 and the surface of the optical modulation and thedistance of the projector pixel at 4771 from the intersection of thereference axis 4776 with the surface of the optical modulator 4770. Thisangle is subtracted from the angle between the baseline and theprojector reference axis to get the desired angle.

The camera 4764 includes a camera lens 4782 and a photosensitive array4780. The camera lens 4782 has a camera lens perspective center 4785 anda camera optical axis 4786. The camera optical axis is an example of acamera reference axis. From a mathematical point of view, any axis thatpasses through the camera lens perspective center may equally easily beused in the triangulation calculations, but the camera optical axis,which is an axis of symmetry for the lens, is customarily selected. Aray of light 4783 travels from the object point 4774 through the cameraperspective center 4785 and intercepts the photosensitive array 4780 atpoint 4781. Other equivalent mathematical methods may be used to solvefor the lengths of the sides of a triangle 4774-4785-4775, as will beclear to one of ordinary skill in the art.

Although the triangulation methods are known to those skilled in theart, some additional technical information is given herein below forcompleteness. Each lens system has an entrance pupil and an exit pupil.The entrance pupil is the point from which the light appears to emerge,when considered from the point of view of first-order optics. The exitpupil is the point from which light appears to emerge in traveling fromthe lens system to the photosensitive array. For a multi-element lenssystem, the entrance pupil and exit pupil do not necessarily coincide,and the angles of rays with respect to the entrance pupil and exit pupilare not necessarily the same. However, the model can be simplified byconsidering the perspective center to be the entrance pupil of the lensand then adjusting the distance from the lens to the source or imageplane so that rays continue to travel along straight lines to interceptthe source or image plane. In this way, the simple model shown in FIG.13A is obtained. It should be understood that this description providesa good first order approximation of the behavior of the light but thatadditional fine corrections can be made to account for lens aberrationsthat can cause the rays to be slightly displaced relative to positionscalculated using the model of FIG. 13A. Although the baseline length,the baseline projector angle, and the baseline camera angle aregenerally used, it does not exclude the possibility that other similarbut slightly different formulations of the model may be applied withoutloss of generality in the description given herein.

In some cases, a scanner system may include two cameras in addition to aprojector. In other cases, a triangulation system may be constructedusing two cameras alone, wherein the cameras are configured to imagepoints of light on an object or in an environment. For the case in whichtwo cameras are used, whether with or without a projector, atriangulation may be performed between the camera images using abaseline between the two cameras. In this case, the triangulation may beunderstood with reference to FIG. 13A, with the projector 2562 replacedby a camera.

In some cases, different types of scan patterns may be advantageouslycombined to obtain better performance in less time. For example, in anembodiment, a fast measurement method uses a two-dimensional codedpattern in which three-dimensional coordinate data may be obtained in asingle shot. In a method using coded patterns, different characters,different shapes, different thicknesses or sizes, or different colors,for example, may be used to provide distinctive elements, also known ascoded elements or coded features. Such features may be used to enablethe matching of the point 2571 to the point 2581. A coded feature on thesource pattern of light 2570 may be identified on the photosensitivearray 2580.

An advantage of using coded patterns is that three-dimensionalcoordinates for object surface points can be quickly obtained using asingle image of an area. However, a sequential structured lightapproach, such as the sinusoidal phase-shift approach discussed above,may give more accurate results. Therefore, the user may advantageouslychoose to measure certain objects or certain object areas or featuresusing different projection methods according to the accuracy desired. Byusing a selectable source pattern of light, such a selection may bechanged as desired by the operator to provide the desired result.

A line emitted by a laser line scanner intersects an object in a linearprojection. The illuminated shape traced on the object is twodimensional. In contrast, a projector that projects a two-dimensionalpattern of light creates an illuminated shape on the object that isthree dimensional. One way to make the distinction between the laserline scanner and the structured light scanner is to define thestructured light scanner as a type of scanner that contains at leastthree non-collinear pattern elements. For the case of a two-dimensionalcoded pattern of light, the three non-collinear pattern elements arerecognizable because of their codes, and since they are projected in twodimensions, the at least three pattern elements must be non-collinear.For the case of the periodic pattern, such as the sinusoidally repeatingpattern, each sinusoidal period represents a plurality of patternelements. Since there is a multiplicity of periodic patterns in twodimensions, the pattern elements must be non-collinear. In contrast, forthe case of the laser line scanner that emits a line of light, all ofthe pattern elements lie on a straight line. Although the line haswidth, and the tail of the line cross section may have less opticalpower than the peak of the signal, these aspects of the line are notevaluated separately in finding surface coordinates of an object andtherefore do not represent separate pattern elements. Although the linemay contain multiple pattern elements, these pattern elements arecollinear.

It should be noted that although the descriptions given abovedistinguish between line scanners and area (structured light) scannersbased on whether three or more pattern elements are collinear, it shouldbe noted that the intent of this criterion is to distinguish patternsprojected as areas and as lines. Consequently patterns projected in alinear fashion having information only along a single path are stillline patterns even though the one-dimensional pattern may be curved.

As explained herein above, an LLP or area scanner may be used with anAACMM to obtain the position and orientation of the LLP or area scanner.Another method of measuring with an LLP is to remove the LLP from theAACMM and hold it by hand. The position and orientation of the LLP orarea scanner relative to an object may be determined by registeringmultiple scans together based on commonly observed features.

It is also known to use scanner 2500, which might be a line scanner orarea scanner, with a six-DOF (degree-of-freedom) laser tracker 900 asshown in FIG. 14A. The scanner 2505 includes a projector 2520 that in anembodiment projects a two dimensional pattern of light (structuredlight). Such light emerges from the projector lens perspective centerand travels in an expanding pattern outward until it intersects theobject 2528. Examples of this type of pattern are the coded pattern andthe periodic pattern, as explained herein above. In another embodiment,the projector 2520 may project a one-dimensional pattern of light,thereby performing as an LLP or line scanner.

An exemplary laser tracker system 4005 illustrated in FIG. 14B includesa laser tracker 4010, a retroreflector target 4026, an optionalauxiliary unit processor 4050, and an optional auxiliary computer 4060.An exemplary gimbaled beam-steering mechanism 4012 of laser tracker 4010comprises a zenith carriage 4014 mounted on an azimuth base 4016 androtated about an azimuth axis 4020. A payload 4015 is mounted on thezenith carriage 4014 and rotated about a zenith axis 4018. Zenith axis4018 and azimuth axis 4020 intersect orthogonally, internally to tracker4010, at gimbal point 4022, which is typically the origin for distancemeasurements. A laser beam 4046 virtually passes through the gimbalpoint 4022 and is pointed orthogonal to zenith axis 4018. In otherwords, laser beam 4046 lies in a plane approximately perpendicular tothe zenith axis 4018 and that passes through the azimuth axis 4020.Outgoing laser beam 4046 is pointed in the desired direction by rotationof payload 4015 about zenith axis 4018 and by rotation of zenithcarriage 4014 about azimuth axis 4020. A zenith angular encoder,internal to the tracker, is attached to a zenith mechanical axis alignedto the zenith axis 4018. An azimuth angular encoder, internal to thetracker, is attached to an azimuth mechanical axis aligned to theazimuth axis 4020. The zenith and azimuth angular encoders measure thezenith and azimuth angles of rotation to relatively high accuracy.Outgoing laser beam 4046 travels to the retroreflector target 4026,which might be, for example, a spherically mounted retroreflector (SMR)as described above. By measuring the radial distance between gimbalpoint 4022 and retroreflector 4026, the rotation angle about the zenithaxis 4018, and the rotation angle about the azimuth axis 4020, theposition of retroreflector 4026 is found within the spherical coordinatesystem of the tracker.

Outgoing laser beam 4046 may include one or more laser wavelengths, asdescribed hereinafter. For the sake of clarity and simplicity, asteering mechanism of the sort shown in FIG. 14B is assumed in thefollowing discussion. However, other types of steering mechanisms arepossible. For example, it is possible to reflect a laser beam off amirror rotated about the azimuth and zenith axes. The techniquesdescribed herein are applicable, regardless of the type of steeringmechanism.

Several laser trackers are available or have been proposed for measuringsix, rather than the ordinary three, degrees of freedom. Exemplary sixdegree-of-freedom (six-DOF) systems are described by U.S. Pat. No.7,800,758 ('758) to Bridges et al., U.S. Pat. No. 8,525,983 ('983) toBridges et al., U.S. Pat. No. 6,166,809 ('809) to Pettersen et al., andU.S. Patent Application No. 2010/0149525 ('525) to Lau, the contents allof which are incorporated by reference. Six-DOF systems providemeasurements of three orientational degrees-of-freedom as well as threepositional degrees-of-freedom (i.e., x, y, z).

FIG. 14A shows an embodiment of a six-DOF scanner 2500 used inconjunction with a six-DOF laser tracker 900. The six-DOF laser tracker900 sends a beam of light 784 to a retroreflector 2510, 2511 on thesix-DOF scanner 2500. The six-DOF tracker 900 measures the distance fromthe tracker 900 to scanner 2500 with a distance meter (not shown) in thetracker, and it measures two angles from the tracker 900 to the six-DOFscanner 2500 using two angle transducers such as angular encoders (notshown). The six-DOF scanner 2500 includes a body 2514, one or moreretroreflectors 2510, 2511 a scanner camera 2530, a scanner lightprojector 2520, an optional electrical cable 2546, an optional battery2444, an antenna 2548, and electronics circuit board 2542. The antenna2548 if present provides wireless communication between the six-DOFscanner 2500 and other computing devices such as the laser tracker 900and external computers. The scanner projector 2520 and the scannercamera 2530 together are used to measure the three dimensionalcoordinates of a workpiece 2528. The camera 2530 includes a camera lenssystem 2532 and a photosensitive array 2534. The photosensitive array2534 may be a CCD or CMOS array, for example. The scanner projector 2520includes a projector lens system 2523 and a source pattern of light2524. The source pattern of light may emit a point of light, a line oflight, or a structured (two dimensional) pattern of light. If thescanner light source emits a point of light, the point may be scanned,for example, with a moving mirror, to produce a line or an array oflines. If the scanner light source emits a line of light, the line maybe scanned, for example, with a moving mirror, to produce an array oflines. In an embodiment, the source pattern of light might be an LED,laser, or other light source reflected off a digital micromirror device(DMD) such as a digital light projector (DLP) from Texas Instruments, anliquid crystal device (LCD) or liquid crystal on silicon (LCOS) device,or it may be a similar device used in transmission mode rather thanreflection mode. The source pattern of light might also be a slidepattern, for example, a chrome-on-glass slide, which might have a singlepattern or multiple patterns, the slides moved in and out of position asneeded. Additional retroreflectors, such as retroreflector 2511, may beadded to the first retroreflector 2510 to enable the laser tracker totrack the six-DOF scanner from a variety of directions, thereby givinggreater flexibility in the directions to which light may be projected bythe six-DOF projector 2500.

The six-DOF scanner 2500 may be held by hand or mounted, for example, ona tripod, an instrument stand, a motorized carriage, or a robot endeffector. The three dimensional coordinates of the workpiece 2528 ismeasured by the scanner camera 2530 by using the principles oftriangulation. There are several ways that the triangulation measurementmay be implemented, depending on the pattern of light emitted by thescanner light source 2520 and the type of photosensitive array 2534. Forexample, if the pattern of light emitted by the scanner light source2520 is a line of light or a point of light scanned into the shape of aline and if the photosensitive array 2534 is a two dimensional array,then one dimension of the two dimensional array 2534 corresponds to adirection of a point 2526 on the surface of the workpiece 2528. Theother dimension of the two dimensional array 2534 corresponds to thedistance of the point 2526 from the scanner light source 2520. Hence thethree dimensional coordinates of each point 2526 along the line of lightemitted by scanner light source 2520 is known relative to the localframe of reference of the six-DOF scanner 2500. The six degrees offreedom of the six-DOF scanner are known by the six-DOF laser trackerusing the methods described in patent '758. From the six degrees offreedom, the three dimensional coordinates of the scanned line of lightmay be found in the tracker frame of reference, which in turn may beconverted into the frame of reference of the workpiece 2528 through themeasurement by the laser tracker of three points on the workpiece, forexample.

If the six-DOF scanner 2500 is held by hand, a line of laser lightemitted by the scanner light source 2520 may be moved in such a way asto “paint” the surface of the workpiece 2528, thereby obtaining thethree dimensional coordinates for the entire surface. It is alsopossible to “paint” the surface of a workpiece using a scanner lightsource 2520 that emits a structured pattern of light. In an embodiment,when using a scanner 2500 that emits a structured pattern of light, moreaccurate measurements may be made by mounting the six-DOF scanner on atripod or instrument stand. The structured light pattern emitted by thescanner light source 2520 might, for example, include a pattern offringes, each fringe having an irradiance that varies sinusoidally overthe surface of the workpiece 2528. In an embodiment, the sinusoids areshifted by three or more phase values. The amplitude level recorded byeach pixel of the camera 2530 for each of the three or more phase valuesis used to provide the position of each pixel on the sinusoid. Thisinformation is used to help determine the three dimensional coordinatesof each point 2526. In another embodiment, the structured light may bein the form of a coded pattern that may be evaluated to determinethree-dimensional coordinates based on single, rather than multiple,image frames collected by the camera 2530. Use of a coded pattern mayenable relatively accurate measurements while the six-DOF scanner 2500is moved by hand at a reasonable speed.

In some cases, it is advantageous to measure the features such as edgesor holes using an optional tactile probe 2550 attached to the six-DOFscanner 2500. The tactile probe 2550 in FIG. 14A includes such as aprobe tip 2554, which is part of a probe extension assembly 2550. In anembodiment, the projector 2520 sends a laser beam to illuminate theregion to be measured.

As explained herein above, the laser tracker 900 measures a distance andtwo angles to determine three positional degrees-of-freedom (x, y, z) ofthe six-DOF scanner 2500. There are many possible methods of determiningthe three orientational degrees-of-freedom of the six-DOF scanner 2500.These methods are described in more detail herein below.

As explained herein above, a measurement device such as a tactile probe,LLP, or area scanner may be attached to an AACMM. Alternatively, themeasurement device may be held by hand with registration provided bymatching of registration targets or by measuring of a six-DOF targetwith a laser tracker. In another alternative, illuminated markers areattached to a measurement device, which might for example be a tactileprobe, line scanner, or area scanner. The illuminated markers aremeasured with a camera bar having two or more cameras. With this method,the position and orientation of the measurement device can be foundwithin a desired frame of reference.

FIG. 15A is a perspective view of a three-dimensional tactile probingsystem 5100 that includes a camera bar 5110 and a probe assembly 5140.The camera bar includes a mounting structure 5112 and at least twotriangulation cameras 5120, 5124. It may also include an optional camera5122. The cameras each include a lens and a photosensitive array, forexample, as shown in the lens 2564 of FIG. 13A. The optional camera 5122may be similar to the cameras 5120, 5124 or it may be a color camera.The probe assembly 5140 includes a housing 5142, a collection of lights5144, optional pedestals 5146, shaft 5148, stylus 5150, and probe tip5152. The position of the lights 5144 are known relative to the probetip 5152. The lights may be light sources such as light emitting diodesor they might be reflective spots that may be illuminated by an externalsource of light. Factory or on-site compensation procedures may be usedto find these positions. The shaft may be used to provide a handle forthe operator, or another handle may be provided.

Triangulation of the image data collected by the cameras 5120, 5124 ofthe camera bar 5110 are used to find the three-dimensional coordinatesof each point of light 5144 within the frame of reference of the camerabar. Throughout this document, and in the claims, the term “frame ofreference” is taken to be synonymous with the term “coordinate system.”Mathematical calculations, which are well known in the art, are used tofind the position of the probe tip within the frame of reference of thecamera bar. By bringing the probe tip 5152 into contact with an object5160, surface points on the object can be measured.

An electrical system 5101 may include an electrical circuit board 5102and an external computer 5104. The external computer 5104 may comprise anetwork of computers. The electrical system 5101 may include wired andwireless portions, either internal or external to the components of FIG.15A that carry out the measurements and calculations to obtainthree-dimensional coordinates of points on the surface. In general, theelectrical system 5101 will include one or more processors, which may becomputers, microprocessors, field programmable gate arrays (FPGAs), ordigital signal processing (DSP) units, for example.

FIG. 15B is a perspective view of a three-dimensional area scanningsystem 5200 that includes a camera bar 5110 and a scanner assembly 5240.The camera bar was described herein above in reference to FIG. 15A. Thescanner assembly 5240 includes a housing 5142, a collection of lights5144, optional pedestals 5146, shaft 5148, projector 5252, and camera5254. The characteristics of the housing 5142, lights 5144, optionalpedestals 5146, and shaft 5148 were described hereinabove in referenceto FIG. 15A. The projector 5252 projects light onto the object 5160. Theprojector 5252 may be a variety of types, for example, LED, laser, orother light source reflected off a digital micromirror device (DMD) suchas a digital light projector (DLP) from Texas Instruments, a liquidcrystal device (LCD) or liquid crystal on silicon (LCOS) device. Theprojected light might come from light sent through a slide pattern, forexample, a chrome-on-glass slide, which might have a single pattern ormultiple patterns, the slides moved in and out of position as needed.The projector 5252 projects light 5262 into an area 5266 on the object5160. A portion of the illuminated area 5266 is imaged by the camera5254 to obtain digital data.

The digital data may be partially processed using electrical circuitrywithin the scanner assembly 5240. The partially processed data may beprovided to a system 5201 that includes an electrical circuit board 5202and an external computer 5204. It should be appreciated that theexternal computer 5204 may comprise a network of computers. Theelectrical system 5201 may include wired and wireless portions, eitherinternal or external to the components of FIG. 15B, that carry out themeasurements and calculations to obtain three-dimensional coordinates ofpoints on the surface 5160. In general, the system 5201 may include oneor more processors, which may be computers, microprocessors, fieldprogrammable gate arrays (FPGAs), or digital signal processing (DSP)units, for example. The result of the calculations is a set ofcoordinates in the camera bar frame of reference, which may in turn beconverted into another frame of reference, if desired.

FIG. 15C is a perspective view of a three-dimensional line scanningsystem 5300 that includes a camera bar 5110 and a scanner assembly 5340.The camera bar was described hereinabove in reference to FIG. 15A. Thescanner assembly 5340 includes a housing 5142, a collection of lights5144, optional pedestals 5146, shaft 5148, projector 5352, and camera5354. The characteristics of the housing 5142, lights 5144, optionalpedestals 5146, and shaft 5148 were described hereinabove in referenceto FIG. 15A. The projector 5352 projects light onto the object 5160. Theprojector 5352 may be a source of light that produces a stripe of light,for example, a laser that is sent through a cylinder lens or a Powelllens, or it may be a DLP or similar device also having the ability toproject 2D patterns, as discussed hereinabove in reference to FIG. 15B.The projector 5352 projects light 5362 in a stripe 5366 onto the object5160. A portion of the stripe pattern on the object is imaged by thecamera 5354 to obtain digital data. The digital data may be processed ina manner similar to that described in reference to FIG. 15B using forexample electrical components 5201. The result of the calculations is aset of three-dimensional coordinates of the object surface in thecamera-bar frame of reference, which may in turn be converted intoanother frame of reference, if desired.

FIG. 16 is an isometric view of a 3D measuring device 1700 configuredfor attachment to an articulated arm CMM 100 through a mechanical andelectrical interface 426, which in this case includes the connector426A. Electrical signals are passed between the 3D measuring device 1700and any device attached to the electrical connector 434. For example,the attachment may be to an articulated arm CMM through the connector426C, or it may be to a different connector when the 3D measuring device1700 is used in a handheld mode or a production line mode.

In an embodiment, measuring device 1700 includes a scanner 507 having aprojector 510 and a camera 508. The projector 510 may project a point oflight, a line of light, or a pattern of light that covers an area. Theprinciples of operation of a line scanner and an area scanner arediscussed herein above. In some cases, two or more cameras may be usedwith either type of scanner. In an embodiment, the projector 510 mayinclude a digital micromirror device (DMD) capable of projecting anytype of pattern. For example, a DMD can project any desired structuredpattern of light over an area. It may project a line of light at anyangle, and it may sweep the line of light. The DMD may alternativelysweep a spot of light. Sweeping a line or a spot of light is a usefultechnique for reducing or eliminating multipath interference, which suchinterference is observed to have occurred or is expected to haveoccurred based on geometry of the object being scanned.

In an embodiment, the cameras 1750A, 1750B form a stereo camera pair. Inan embodiment, the cameras 1750A, 1750B determine 3D coordinates oftargets within a frame of reference of the 3D measuring device 1700. Inan embodiment, the cameras 1752A, 1752B determine the 3D coordinates ofreflective targets within a field-of-view (FOV) of the cameras 1750A,1750B. The targets may be located on or proximate an object under test.In an embodiment, the reflective targets are illuminated by light fromlight sources 1752A, 1752B. In an embodiment, the light sources 1752A,1752B are light-emitting diodes (LEDs). In another embodiment, thecameras 1752A, 1752B determine the 3D coordinates of light sources suchas LEDs on or proximate an object under test. In another embodiment, thecameras 1752A, 1752B determine the 3D coordinates of light marks, suchas spots of light, projected onto the object by an external projectorfixed with respect to the object. In the exemplary embodiment, the lightsources 1752A, 1752B are disposed about the periphery of the cameras1750A, 1750B.

In an embodiment, the light sources 1752A, 1752B are configured toproject light at a wavelength different than to which the scanner camera508 is sensitive. For example, the camera 508 may be configured torespond to blue light at 450 nm, with the optics coated to block lightoutside a band of blue wavelengths. In this case, the light sources1752A, 1752B may be configured to emit a different wavelength, forexample, a near infrared wavelength of 800 nm. In this case, the cameras1750A, 1750B may be coated to reduce or eliminate light from the bluewavelengths emitted by the scanner projector. This arrangement ofwavelengths may be advantageous if the scanner 507 operatessynchronously with the stereo camera pair 1750A, 1750B. In other cases,the cameras 1750A, 1750B may be configured to respond to the wavelengthsemitted by the projector 510. This might be advantageous, for example,to enable the stereo camera pair to independently determine the 3Dcoordinates of a line or pattern of light emitted by the projector 510.

In an embodiment, the 3D coordinates of widely distributed markers on orproximate an object are determined in a global frame of reference usinga photogrammetry. In an embodiment, the photogrammetry system includes acamera and a calibrated scale bar, with the camera used to measure themarkers and the calibrated scale bar in a plurality of digital 2Dimages. By processing the multiple 2D images, the 3D coordinates of thecollection of markers may be determined in a common (global) frame ofreference. Such a method may be advantageous when measuring a largeobject, especially when using relatively few markers.

In another embodiment, a single camera 1750A or 1750B is used tocaptures 2D images of markers. If the camera 1750A or 1750B has arelatively wide FOV, the markers in the plurality of captured images mayprovide continuity to the scanner system in registering the plurality of3D scanner coordinates collected in successive frames.

In an embodiment, the 3D measuring device 1700 further includes a colorcamera 1760. The colors captured by the color camera 1760 may be used toadd color to a 3D image captured by the scanner 507. Such coloration issometimes referred to as adding texture to a 3D image because it mayreveal such aspects of surface roughness, surface reflectance properties(such as shininess or transparency), and shadows. In an embodiment,light sources 1762 may be used to increase the light applied to anobject or to apply particular wavelengths of light. For example,infrared light may be projected from the lights 1762 to enable a map ofobject temperature to be overlaid on the captured 3D image. In otherembodiments, the lights 1762 may project over a broad spectrum toprovide a more desirable lighting than would be provided by artificiallight such as that provided by fluorescent lights, which may produce agreen hue. In the exemplary embodiment, the light sources 1762 aredisposes about the periphery of the color camera 1760.

In an embodiment, power is provided to the 3D measuring device 1700 by abattery 1710, which may be located in the camera/scanner portion of theassembly 1700, in the handle 504, beneath the handle, or attached as aseparate assembly. In an embodiment, the battery is convenientlyremovable and replaceable. In an embodiment, the 3D measuring assembly1700 may be removed from the AACMM 100 without first turning off thepower of either the AACMM 100 or the 3D measuring assembly 1700.

In an embodiment, a wireless communication system 1730 includes anantenna and wireless electronics, which might for example be based onIEEE 802.3 (Ethernet), IEEE 802.11 (Wi-Fi) or IEEE 802.15 (Bluetooth).In an embodiment, the 3D measuring device 1700 includes a processor 1720capable of performing calculations such as image capture, triangulation,and registration of multiple 3D images. In an embodiment, the processorfurther includes a real-time bus, which might be EtherCAT, SERCOS III,PROFINET, POWERLINK, or EtherNet/IP, for example. It should beappreciated that the processor 1720 may include into or coupled toassociated circuitry, such as analog-to-digital converters, networkinterfaces, display or video processors, input/output controllers,non-volatile memory and read-only memory circuits for example.

In an embodiment, the 3D measuring assembly 1700 includes a display1740. In an embodiment, the display is a touch-screen display. In anembodiment, the display 1740 shows the results of 3D measurements duringoperation of the measurement device 1700. In an embodiment, the displayfurther includes a user interface that offers the user choices in howthe measurement is performed or data is processed or transferred.

FIGS. 17A, 17B, and 17C show perspective, top, and sectional views of aconnector assembly 426B according to an embodiment. As will be discussedin more detail below, the connector assembly 426B may be incorporatedinto another device to allow the device to couple with the connectorassembly 426A shown in FIGS. 10C, 11A, 11B, 16. The connector 426A isfurther configured to couple to a connector assembly 426C of the AACMM100. In an embodiment illustrated in FIG. 10C and FIG. 5, an end probe401is coupled to a connector assembly 426C to a connector assembly 426Aby the tightening of a collar 438, as explained herein above. In anembodiment, the connector assembly 426B is configured to attach directlyto a connector 426A on a handheld device such as the scanner 500 or a 3Dmeasuring device 1700.

In an embodiment, the connector assembly 426B includes a body 3710, a3710, an electrical connector 3720, a front lip 3732, a rear lip 3734,and a locking assembly 3740. In an embodiment, the locking assembly 3740includes a rotating handle 3742, a handle pin 3743, a rotating plate3744, a curved CAM slot 3746, and a translator pin 3748. In anembodiment, the translator pin 3748 is fixed relative to the lip 3734and is further located along a center line of the handle pin 3743. Asthe handle is rotated in a direction 3750, there is a decrease in thedistance from the handle pin 3743 to the curved CAM slot 3746 at theposition of the translator pin 3748. The handle pin 3743 remains fixedrelative to the body 3710 because the rotating plate 3744 is constrainedto rotate within a cylinder cut into the body 3710. Hence, as the handle3742 is rotated in a direction 3750, the translator pin 3748 and the lip3734 are moved toward the back of the connector assembly 426B, in thedirection of the handle pin 3743.

With the handle 3742 rotated in the direction 3750, the front lip 3732is slid underneath the lip 444 shown in FIGS. 11A, 11B. The electricalconnectors 3720 and 434 are pressed together, and the handle 3742 ismoved in the 3742 is moved in the direction 3752 to lock the rear lip3734 to the lip 454. In this manner, an accessory unit having aconnector 426B may be quickly and securely locked to a connector 426A ofa dimensional measuring device. It should be appreciated that othertypes of interlocking connector assemblies may be used in theembodiments described herein to couple the connector 426A with anotherdevice and the illustrated embodiment is not intended to be limiting.

FIGS. 18A, 18B, 18C, and 18D show a scanner 500 configured forattachment to a camera assembly 1850 through a mechanical and electricalinterface 426, which in this case includes the connectors 426A and 426B.The connector may 426B differ from the connector 426C in FIG. 10C, asdescribed herein above, but both connectors (such as 426B, 426C) arecompatible with the connector 426A. Electrical signals are passedbetween the scanner 500 and the camera assembly 1850 through anelectrical connector 434. The electrical interface 426 includes twoparts, a first part 426A, which in this case is a scanner connector426A, and a second part 426B, which in this case is a camera assemblyconnector 426B. The first part and the second part couple together tohold the scanner 500 is fixed position and orientation relative to thecamera assembly 1350.

In an embodiment, the camera assembly 1850 includes at least one camera.In another embodiment, the camera assembly 1850 includes two cameras1853A, 1853B. The camera 1853A includes a lens assembly 1854A and anelectronics housing 1856A that includes a photosensitive array (notshown). The camera 1853B includes a lens assembly 1854B and anelectronics housing 1856B that includes a photosensitive array, togetherwith support electronics, which may include a processor 1885. In anembodiment, the processor 1885 may process 2D image data obtained fromthe photosensitive array, and the processor 1885 may further cooperatewith a controller 512 within the scanner 500 to register the multiplesets of 3D coordinates provided ty scanner 500. In an embodiment, thecameras 1853A, 1853B have fields-of-view (FOVs) that partially overlap,thereby providing stereo imaging. Such imaging enables determination of3D coordinates of targets using triangulation methods as describedherein above. In some embodiments, the cameras together provide a FOVlarger than the camera 508. In other embodiments, the cameras togetherprovide a smaller FOV than the camera 508. In some embodiments, a singlewide FOV camera is provided on the assembly 1850. In other cases,several wide FOV, but non-overlapping, cameras are provided on thecamera assembly 1850. In an embodiment, computing actions may further beprovided by a processor 1886.

In an embodiment, power is provided to the scanner 500 and cameraassembly 1850 by a battery 1882 (FIG. 18C), which may be located in thecamera assembly, in the scanner assembly, attached beneath the handle,or attached as a separate assembly. In an embodiment, the battery isrechargeable. In an embodiment, the battery is conveniently removed andreplaced. In an embodiment, the battery may be hot-swapped, that is,removed while the unit is operational.

In an embodiment, a wireless system 1884 that includes an antennacommunicates with devices external to the scanner 500 and cameraassembly 1850. In an embodiment, the wireless system 1884 exchanges datawith a computer network. The wireless system 1884 if present may belocated in the camera assembly 1850, the scanner 500, external to thesecomponents, or in a combination of these components.

In an embodiment, the camera assembly 1850 (FIGS. 18B, 18C) furtherincludes a display 1883. In an embodiment, the display includes atouchscreen. In an embodiment, the display may show results ofmeasurements in real time, display messages, or enable interface by auser through the touchscreen.

Referring now to FIGS. 18C, 18D, in an embodiment, the combined scanner500 and camera assembly 1850 may include an electrical connectorassembly 1890 having a connector 1892, protective cap 1894, and tether1896. In an embodiment, the connector 1892 connects to a cable 1897 thatattaches to an electronics unit 1898 having a power supply 1872 and aprocessor 1874. In an embodiment, the electronics unit 1898 may connectto other components through an electrical cable 1899. In an embodiment,the electrical cable 1899 is an industrial real-time bus connected toand synchronized with other devices in an industrial automation network.In an embodiment, electronics in the electronics unit 1899 includeselectronics to provide a time-stamp according to IEEE 1588. In anembodiment, the electrical line 1899 is a real-time bus, which might beEtherCAT, SERCOS III, PROFINET, POWERLINK, or EtherNet/IP, for example.Such a real-time bus may attach to dozens or hundreds of other devicesin an automation network.

In an embodiment where the scanner 500 is an LLP, then the 3Dcoordinates are projected on a line, which is to say that the 3Dcoordinates are found in the line of light sent from the projector 510onto an object. In an embodiment where the scanner 500 is an areascanner, then the 3D coordinates are projected in a 2D area on thesurface of the object. If the scanner 500 is removed from the AACMM 100and moved by hand to determine 3D coordinates of an object surface, itis desirable to register the multiple collections of 3D coordinatesobtained from individual scans by the scanner 500. In the case of an LLPscanner 500, the individual scans to be registered are line scans. Inthe case of an area scanner 500, the individual scans to be registeredare area scans.

It is known from prior art to attach an LLP or an area scanner to anAACMM, as shown for example in FIG. 10B. In the case of an area scanner,it is also known to use the area scanner in a handheld mode afterremoving the scanner from the AACMM, as disclosed in U.S. Pat. No.8,832,954 ('954) to Atwell et al., the contents of which areincorporated by reference. Multiple scans obtained from the handheldarea scanner are registered together using features of the scannedobject, where the features are obtained from the 3D coordinates obtainedusing methods of triangulation described herein above with reference toFIGS. 13A and 13B. It is not generally possible to use an LLP in ahandheld mode, on its own, after removing the LLP from the AACMM becauseindividual LLP scans, each along a single plane, do not provide featureinformation in two dimensions on which to obtain registration based onfeatures.

In an embodiment, the projector of a scanner may include a digitalmicromirror device (DMD) capable of projecting any type of pattern. Forexample, a DMD can project any desired structured pattern of light overan area. It may project a line of light at any angle, and it may sweepthe line of light. In another embodiment, the DMD may sweep a spot oflight. Sweeping a line or a spot of light is an advantageous techniquefor reducing or eliminating multipath interference, which suchinterference is observed to have occurred or is expected to haveoccurred based on geometry of the object being scanned.

Methods are now described for using the camera assembly 1350 incombination with the scanner 500 to register multiple scans obtained bythe scanner 500, thereby enabling scans to be taken in a handheld mode,with an operator holding the scanner 500 by the handle 504 and movingthe scanner 500 over the surface of an object to be measured.

For all of the methods described herein below, a preliminary step is toobtain a common frame of reference for the scanner 500 and cameraassembly 1850. Such a preliminary step may be carried out at themanufacturer's factory or by the operator by performing predeterminedprocedures. The common frame of reference can be obtained, for example,by viewing common features with the scanner 500 and camera assembly1850, and then performing a least-squares optimization procedure tomatch the observed features. Such methods are known in the art and arenot discussed further.

FIG. 18E illustrates a first method for using the cameras 1853A, 1853Bto register multiple 3D coordinates obtained from line scans taken by anLLP scanner 500, wherein the registration is based on the matching ofnatural features. In a first instance, a first line of light 1810 isprojected by the projector 510 onto an object 1801. In some regions, theobject 1801 may include some fine details, as in the features 1802 and1803, and in other regions, the object 1801 may include large regions1804 that have few features. The first line of light 1810 is viewed bythe 2D image sensor (e.g., photosensitive array) of the camera 508 in aregion 1815 of the object imaged by the camera 508. As explained hereinabove with reference to FIG. 12, the appearance of the first line oflight 1810 on the 2D image sensor of the camera 508 provides theinformation for a processor in the system to determine the 3Dcoordinates of the first line of light on the object 1801, where the 3Dcoordinates are given in the frame of reference of the scanner 500.

In a second instance, a second line of light 1812 is projected by theprojector 510 onto the object 1801. The appearance of the second line oflight 1812 on the 2D image sensor of the camera 508 provides theinformation for the processor in the scanner 500 to determine the 3Dcoordinates of the second line of light, again in the frame of referenceof the scanner 500. It is desired to register scans in the firstinstance and the second instance so that the 3D coordinates of the firstline of light and the second line of light are put into a common frameof reference.

In a first method of registration natural features of the object areused. The cameras 1853A, 1853B image a region 1820 of the object. In theillustrated example, features 1806, 1807, and 1808 are imaged by thecameras 1853A, 1853B. Using triangulation, a processor in the system usethe images of the cameras 1853A, 1853B find the 3D coordinates of thesedetailed features in the frame of reference of the scanner 500. Asexplained herein above, such triangulation requires a baseline distancebetween the camera 1853A and 1853B and the relative orientation of thesecameras relative to the baseline. Because the 3D coordinates of thefeatures captured by the cameras 1853A, 1853B cover an area of theobject 1801, rather than just a line, it may be possible to match thefeatures in 2D, thereby determining the coordinate transformation toplace the first line of light 1810 and the second line of light 1812 inthe same frame of reference. Some natural features such as the point ofintersection of three planes 1809 in FIG. 18E have an unambiguousposition in 3D space. Such features may be matched in multiple cameraimages and hence are particularly useful in registering images based onnatural targets.

FIG. 18F illustrates a second method for using the cameras 1853A, 1853Bto register multiple 3D coordinates obtained from line scans taken by anLLP scanner 500, wherein the registration is based on the matching ofphysical targets rather than natural targets. FIG. 18F is the same asFIG. 18E except that FIG. 18F further includes markers 1832 on theobject 1801 and/or markers 1834 in the vicinity of the object but not onthe object. In an embodiment, the targets are reflective targets, forexample, white circular targets sometimes referred to as photogrammetrytargets. In an embodiment, such targets are illuminated by light sources1858A, 1858B shown in FIGS. 18A and 18B. In other embodiments, thetargets 1832, 1834 are illuminated by ambient light sources or by otherlight sources separate from the camera assembly 1350. In an embodiment,the targets 1832, 1834 are themselves light sources, for example, LEDs.In an embodiment, the targets 1832, 1834 are a combination ofphotogrammetry targets and LEDs.

In a first instance, the projector 510 projects a first line of light1810 onto the object 1801. In a second instance, the projector 510projects a second line of light 1812 onto the object 1801. In anembodiment, in each of the first and second instances, the cameras1853A, 1853B each image three common non-collinear targets, which mightbe 1832, 1834. These three points enable a processor in the system toplace the 3D coordinates obtained from the first and second lines oflight in a common frame of reference. This registration procedure iscarried out repeatedly as the handheld scanner 500 is moved across theobject 1801, thereby enabling the processor to determine 3D coordinatesof the surface of the object 1801. In another embodiment, imageinformation provided by physical targets is combined with imageinformation provided by natural targets to register together 3Dcoordinates from line scans to obtain 3D coordinates over the surface ofthe object 1801.

FIG. 18G illustrates a third method for using the cameras 1853A, 1853Bto register multiple 3D coordinates obtained from line scans taken by anLLP scanner 500, wherein the registration is based on the matching ofprojected spots of light rather than physical targets or naturaltargets. An external projector 1840 separate from the scanner 500 andcamera assembly 1350 projects spots of light 1832 onto the object and/orspots of light 1834 off the object but in the vicinity of the object.The cameras 1853A, 1853B image these spots of light in the same way theyimaged the physical targets in FIG. 18F, and the processor determines 3Dcoordinates of the object surface in the same manner in each case.

FIG. 18H illustrates a first method for using the cameras 1853A, 1853Bto register multiple 3D coordinates obtained from area scans taken by anarea scanner 500, wherein the registration is based on the matching ofnatural features. In a first instance, a first area of light 1810B isprojected by the projector 510 onto an object 1801. The portion of thefirst area of light 1810B is viewed by the 2D image sensor (e.g.,photosensitive array) of the camera 508 in a region 1815 of the objectimaged by the camera 508. The overlap of the projected region of light1810B and the imaged region 1815 is an overlap region 1817. In thisoverlap region 1817, a processor may determine 3D coordinates of thesurface of the object 1801. These 3D coordinates are found in the frameof reference of the scanner 500.

In a second instance, a second area of light 1812B and the area imagedby the cameras 1853A, 1853B are offset from (as illustrated to the rightof) the first area of light by the projector 510 onto the object 1801,thereby producing a second overlap region 1817B to the adjacent andoffset from the first overlap region 1817. In some cases, there areenough common natural feature details within the first and secondoverlap regions to enable registration of the 3D coordinates in theframe of reference of the scanner 500 in the first and second instancesto be put into a common frame of reference. However, if the object 1801has relatively few features in the overlap regions 1817 and 1817B,register the first and second area scans based on scan data may notprovide desired accuracy.

In an embodiment, the cameras 1853A, 1853B have a wider FOV than thecamera 510, thereby enabling additional features such as 1806, 1807, and1808 to improve the registration by matching of the 3D features asdiscussed herein above using the methods described with respect to FIGS.18E, 18F, and 18G. If an object 1801 lacks distinct features, as in theregion 1804, the registered 3D images may end up warping (e.g. curvingin three-dimensional space). For example, the flat surface in the region1804 may end up looking like a saddle. This effect is sometimescolloquially referred to as the “potato chip” or “potato crisp” effect.

For scanned regions with few features, registration can be improved byproviding targets on or off the object 1801. FIG. 18J illustrates asecond method for using the cameras 1853A, 1853B to register multiple 3Dcoordinates obtained from area scans taken by an area scanner 500,wherein the registration is based on the matching of physical targetsrather than natural targets. FIG. 18J is the same as FIG. 18H exceptthat FIG. 18J further includes markers 1832 on the object 1801 and/ormarkers 1834 in the vicinity of the object but not on the object. Byusing the method described with reference to FIG. 18F, improvedregistration of the 3D coordinates obtained from the successive areascans may in many cases be obtained.

FIG. 18K illustrates a third method for using the cameras 1853A, 1853Bto register multiple 3D coordinates obtained from area scans taken by anarea scanner 500, wherein the registration is based on the matching ofprojected spots of light rather than physical targets or naturaltargets. An external projector 1840 separate from the scanner 500 andcamera assembly 1350 projects spots of light 1832 onto the object and/orspots of light 1834 off the object but in the vicinity of the object.The cameras 1853A, 1853B image these spots of light in the same way theyimaged the physical targets in FIG. 18J, and the processor determines 3Dcoordinates of the object surface in the same manner in each case.

As used herein, the term “mark” may be used to refer to any of thephysical features used to assist in the registration of multiple sets of3D coordinates obtained by the scanner 500 in combination with thecamera assembly 1850. In the discussion herein above, four marks weredescribed: (1) natural features of the object surface (or features on astationary surface proximate the object); (2) LED markers (targets) onthe object or proximate to the object; (3) reflective markers (targets)on the object or proximate the object; and (4) spots of light projectedonto the object or proximate the object by an external projector notlocated on the scanner 500 or camera assembly 1350.

Much of the discussion herein above has described improvements inregistration possible when, for each single determination of 3Dcoordinates of surface points by the scanner 500, three or more marksare viewed by the two cameras 1853A, 1853B on the camera assembly 1350,with any two successive scans having at least three common points.However, in some embodiments, registration is possible based oninformation obtained by a single camera on the camera assembly and byfewer than three marks viewed by the camera. For example, the projectedlight (line of light or area of light) from the projector 510 may alsobe viewed by the one or more cameras 1853A, 1853B and matched along withat least one mark in successive images, thereby providing much moreregistration information in some cases than the marks alone.Furthermore, it is also possible to process data so that registration isnot based entirely on a matching of two 2D images obtained by one ormore cameras on the camera assembly, but on a matching of multiple 2Dimages obtained by one or more cameras obtained on a large number of 2Dimages and on the corresponding large number of 3D images obtained bythe scanner 500.

FIGS. 19A, 19B, 19C, and 19D are isometric, side, side, and front views,respectively, of a detachable six-DOF tracker target assembly 1900coupled to a handheld triangulation scanner 500. FIG. 19E is anisometric view of the detachable six-DOF tracker target assemblyconfigured for coupling to the handheld triangulation scanner. Couplingis made through the mechanical and electrical interface 426. Theelectrical interface 426 includes two parts, a first part 426A, which inthis case is a scanner connector 426A, and a second part 426B, which inthis case is a six-DOF tracker assembly connector 426B. The first partand the second part couple together to hold the scanner 500 is fixedposition and orientation relative to the six-DOF tracker target assembly1900.

In an embodiment, the six-DOF tracker target assembly 1900 furtherincludes a display 1942. In an embodiment, the display 1942 shows 3Dmeasurement data or 2D images. The display 1942 may further indicateannotation for the object or provide a menu in a user interface, forexample, using the touch screen. In an embodiment, the six-DOF trackertarget assembly further includes electronics 1944 that includes abattery and may include a wireless communication channel, including anantenna, and may further include a processor and memory.

The six-DOF tracker target assembly 1900 cooperates with a laser tracker4010 to determine six degrees of freedom of the assembly 1900. The sixdegrees of freedom include three translational degrees of freedom (e.g.,x, y, z), which the tracker determines as explained herein above withreference to FIG. 14B. The tracker also determines three orientationaldegrees of freedom (e.g., pitch, roll, and yaw angles) throughcooperative action with the six-DOF tracker target assembly 1900. Such asix-DOF tracker target assembly may be one of a variety of types, forexample, such as those described in the aforementioned patents '758,'983, '809, and patent application '525, all which are incorporated byreference herein above. By measuring the six degrees of freedom of theconnected six-DOF accessory 1900 and scanner 500, the tracker can trackthe position and orientation of the scanner 500 relative to the object,thereby enabling relatively accurate registration of multiple line scansor area scans. In an embodiment, a probe tip 1915 is attached to a probecoupler 1920. The tracker determines the 3D coordinates of the probe tip1915 based on the measured six degrees of freedom.

In an embodiment, the laser tracker 4010 cooperates with the six-DOFtracker target assembly 1900 and a processor to determine the sixdegrees of freedom of the six-DOF tracker target assembly 1900. In anembodiment, the laser tracker 4010 sends a beam of light to a six-DOFtarget 1930, which may include a retroreflector target that in anembodiment is a cube-corner retroreflector. A collection 1910 ofmultiple six-DOF targets 1930 may be provided to permit convenientviewing of the six-DOF targets from a wide range of angles. A firstportion of the light returning from the retroreflector travels to adistance meter in the laser tracker 4010 to determine a distance fromthe tracker to the retroreflector and a second portion of the lighttravels to a tracker position detector that generates an electricalposition signal indicating the position of the beam of light on theretroreflector. In one mode of operation, the position detector providesthe electrical signal to a control system that includes motors to steerthe beam of light to keep it centered on the retroreflector, therebyenabling tracking of the retroreflector as it is moved. In addition, asexplained herein above, the tracker uses angular transducers such asangular encoders to provide two angles that specify the direction of thelaser beam. With these two angles and the distance provided by thedistance meter, the three translational degrees of freedom are obtainedfor the six-DOF tracker target assembly 1900. Signals from the six-DOFtargets may be sent to an electrical unit 1940 for processing andsynchronization of data.

As explained herein above, many methods are possible for determining thethree orientational degrees of freedom, for example, as described in thepatents '758, '983, '809, and patent application '525. These disclosemethods that include (1) measuring the position of multiple lightsources on a tracker six-DOF target with a camera on the laser trackerto determine the three orientational degrees of freedom; (2) measuringlines marked on a cube-corner retroreflector to determine the threeorientational degrees of freedom; and (3) measuring light passingthrough an opening in a cube-corner retroreflector to determine pitchand yaw angles and measuring angle of inclination to determine rollangle. Other methods of measuring three orientational degrees of freedomare possible, and any method of measuring three orientational degrees offreedom may be used with the six-DOF tracker target assembly 1900.

A preliminary step in the methods described below is to obtain a commonframe of reference for the scanner 500 and six-DOF tracker targetassembly 1900. Such a preliminary step may be carried out at themanufacturer's factory or by the operator by performing proceduresprescribed by the manufacturer. The common frame of reference can beobtained, for example, by viewing common features with the scanner 500and camera assembly 1900, and then performing a least-squaresoptimization procedure to match the observed features. Such methods arewell known in the art and are not discussed further.

In an embodiment, the six-DOF tracker target assembly 1900 furtherincludes a tactile probe 1915, which connects to the collection ofsix-DOF targets 1910 through an interface unit 1920. The interface unitmay provide convenient attaching and detaching of different tactileprobes 1915. It may also provide electrical functionality to some typesof probes such as a “touch probe” that takes a measurement as soon asthe probe touches an object.

In an embodiment, the laser tracker 4010 further measures additionalretroreflector targets in an environment, thereby establishing a frameof reference in the environment. The six-DOF assembly 1900 and scanner500 cooperate with the laser tracker 4010 to determine the position ofan object within the frame of reference of the environment. In anembodiment, in a further step, the tracker 4010 is moved to a newlocation where it re-measures some of the retroreflector targets todetermine its position and orientation in the frame of reference of theenvironment, determined in an earlier step. From its new vantage point,the laser tracker 4010 may cooperate with the six-DOF assembly 4010 andscanner 500 to measure additional sides of the object not previouslyvisible to scanner 500.

Referring now to FIGS. 19B, 19C, in an embodiment, the combined scanner500 and six-DOF assembly 1900 includes an electrical connector assembly1890 having a connector 1892, protective cap 1894, and tether 1896. Inan embodiment, the connector 1892 connects to a cable 1897 that attachesto an electronics unit 1898 having a power supply 1872 and a processor1874. In an embodiment, the electronics unit 1898 connects to othercomponents through an electrical cable 1899. In an embodiment, theelectronics unit attaches to the laser tracker 4010. In an embodiment,the electrical signals traveling on the cable 1897 are synchronizedamong the tracker 4010, the six-DOF assembly 1900, and the scanner 500.In an embodiment, to obtain synchronization a time stamp is provided bythe laser tracker 4010 and a time stamp is also provided by the assemblythat includes the scanner 500 and the six-DOF assembly 1900.

In an embodiment, the electrical cable 1899 is an industrial real-timebus connected to and synchronized with other devices in an industrialautomation network. In an embodiment, electronics in the electronicsunit 1899 includes electronics to provide a time-stamp according to IEEE1588. In an embodiment, the electrical line 1899 is a real-time bus,which might be EtherCAT, SERCOS III, PROFINET, POWERLINK, orEtherNet/IP, for example. Such a real-time bus may attach to dozens orhundreds of other devices in an automation network.

FIG. 20 is an isometric view of a detachable six-DOF target assembly2000 coupled to a handheld triangulation scanner 500. The targets on thesix-DOF target assembly 2000 may be measured with a camera bar, such asthe camera bar 5110 of FIGS. 15-17. In an embodiment, the targets on thesix-DOF target assembly may be measured with two or more camerasseparately mounted in an environment, which is to say, not attached to acommon bar. A camera bar includes two or more cameras spaced apart by acamera-bar baseline. Triangulation is applied to the images of thetargets obtained by the two cameras to determine the six degrees offreedom of the six-DOF target assembly and scanner 500. Additionalgeometrical information such as camera-bar baseline and orientation ofthe cameras in the camera bar are used by a processor in thetriangulation calculation.

In an embodiment, the six-DOF target assembly 2000 includes a collectionof light points 2010, an electrical enclosure 2040, and a tactile probe1915. In an embodiment, the collection of light points 2010 include somepoints 2022 mounted directly to the structure 2012 and other points oflight 2024 mounted on pedestals 2026. In an embodiment, the points oflight 2022, 2024 are LEDs. In another embodiment, the points of light2022, 2024 are reflective spots. In an embodiment, the reflective spotsare illuminated by an external source of light. In an embodiment, thepoints or light are positioned so as to be visible from a wide range ofviewing angles relative to the scanner 500.

In an embodiment, the structure 2012 sits on an electrical enclosure2040 that provides processing and synchronization of data. In anembodiment, the interface 426 includes a scanner connector 426A and anassembly connector 426B. The connectors 426A and 426B are configured todetachably couple the scanner 500 to the target assembly 2000. In anembodiment, a camera bar fixed in place, for example, on a tripod tracksthe six degrees of freedom of the target assembly 2000 and scanner 500while operator holds the scanner by the handle 504 and moves the targetassembly 2000 and scanner 500 over an object. A processor receives datafrom the scanner 500 and target assembly 2000 to register multiple scansof data to obtain 3D coordinates of points on an object surface.

In an embodiment, the six-DOF target assembly includes a tactile probe1915 which connects to the electrical enclosure 2040 through a probeinterface 1920. The probe interface 1920 may provide touch probe oranalog probe electronics. A scanner 500 may provide a lot of detailedinformation quickly, but may provide less information about edges orholes than might be desired. The tactile probe 1915 can be used by theoperator to obtain this desired information.

In an embodiment, the six-DOF target assembly 2000 further includes adisplay 2042. In an embodiment, the display 2042 shows 3D measurementdata or 2D images. The display 2042 may further indicate annotation forthe object or provide a menu in a user interface, for example, using thetouch screen. In an embodiment, the six-DOF tracker target assemblyfurther includes electronics 2044 that includes a battery and mayinclude a wireless communication channel, including an antenna, and mayfurther include a processor and memory.

FIG. 21A shows a triangulation scanner having a removable handle and anattachable accessory, the attachable accessory configured to helpdetermine position and orientation of the triangulation scanner inrelation to an object. In an embodiment, a triangulation scanner 2100includes a removable handle 2154 that may be removed and replaced by anoperator through an attachment 2153, for example, with screws. Unlikethe handle shown in FIG. 11A that includes electrical components, few ifany electrical elements are included in the removable handle 2154. In anembodiment, electrical connections may be provided for the actuators(push buttons) 2164, 2166. In an embodiment, after the handle isremoved, a scanner assembly 2102 includes electrical components movedinto a portion 2106 beneath a portion 2107 that houses the camera 508and projector 510. By providing a flat surface 2108 on the bottom of thelower portion 2106, the scanner 2102 and any other assemblies attachedto it can be conveniently mounted on a robot end effector or next to aconveyor belt of an assembly line. In contrast to a handheldapplication, in which stability of the scanner cannot be assured, bymounting the scanner 2102 on a flat stable surface, it becomes possibleto perform sequential scanning measurements that take longer but aremore accurate. Such measurements, for example, sinusoidal phase shiftmethods, stability is desired between successive measurements.

In an embodiment a camera assembly 1850 is attached through a mechanicaland electrical interface 426 to the scanner 2102. In other embodiments,the camera assembly 1850 in FIG. 21A is replaced with a six-DOF trackertarget assembly 1910 as shown in FIG. 21C, with scanner 500 replaced byscanner 2100B. In another embodiment, the camera assembly 1850 in FIG.21A is replaced with a six-DOF target assembly 2000, such as the six-DOFtarget assembly shown in FIG. 20. The triangulation scanner thatincludes projector 510 and camera 508 may be a laser line probe thatprojects a line of light or an area scanner that projects an area oflight.

For the case in which the scanner 2100B is used on a manufacturingassembly line, a signal from a linear encoder tied to the assembly linemay be sent to the scanner 2100B or to a processor in the system tosynchronize scanner measurements to the assembly line movement. By thismethod, the accuracy of the dimensional scale measured by scanner can beassured. The electrical box 2170 may provide synchronization signals andother signals to and from the scanner 2100B and camera assembly 1850 (orother accessory). Alternatively, the electrical box may transfer timestamps, which might be synchronized through IEEE 1588 methods, or theelectrical box may be attached to a real-time bus 2172 such as EtherCAT,SERCOS III, PROFINET, POWERLINK, or EtherNet/IP.

For the case in which the scanner is held stationary, for example on arobot end effector or next to a moving conveyor belt, the flat bottomtriangulation scanner 2100B may be used. For the case in which a linearencoder provides the scanner 2100B with timing signals from an linearencoder, the scanner 2100B with no additional accessories as shown inFIG. 21B, provides a convenient configuration. For the case in which thescanner is mounted on a robot arm that provides only low accuracyinformation on its movements, the embodiment of FIG. 21C in which asix-DOF tracker target accessory 1900 is attached through an interface426 provides a way to transfer the high accuracy of a six-DOF lasertracker measurement to the measurements made by the scanner 2100B inFIG. 21C.

In an embodiment, the scanner 2100B further includes a color camera 515,as illustrated in FIG. 21B. In an embodiment, a color image captured bythe color camera is used to provide colors for the 3D coordinates ofobject points collected by the scanner 2100B.

FIG. 22 is a front view of a triangulation scanner 2210 that includestwo cameras 2214, 2216 and a projector 2212 arranged in a triangle. Inan embodiment, the scanner also includes a color camera 2218. The handleof the triangulation scanner 2210 may be a removable handle 2154 or apermanently attached handle 504. The triangulation scanner 2210 isconfigured for connection to an articulated arm CMM 100 or alternativelyto an assembly selected from the group consisting of: (1) a six-DOFtracker target assembly 1910 as described in reference to FIGS. 19A-19E;(2) a camera assembly 1850 as described in reference to FIGS. 18A-18D;and (3) a six-DOF light point target assembly as described in referenceto FIG. 20.

Two cameras (a first camera and a second camera) and a projector arearranged in a triangle as shown in FIG. 22. This arrangement has threesets of epipolar line constraints, a first set of constraints for thefirst camera and the second camera, a second set of constraints for thefirst camera and the projector, and a third set of constraints for thesecond camera and the projector. By solving these constraintssimultaneously, it possible to obtain 3D coordinates of points on anobject surface in a single-shot triangulation measurement, even usinguncoded patterns of light. For example, it is possible to determine 3Dcoordinates of projected spots of light obtained from passing lightthrough grating diffractive optical element (DOE), each spot of lightindistinguishable from the others. This method is described more fullyin U.S. Patent Application Publication No. 2014/0168379, the contents ofwhich are incorporated by reference.

To perform the measurement with the triangulation scanner having twocameras and a projector arranged in a triangle as shown in FIG. 22,three separate triangulation measurements are made, one for the twocameras, one for the first camera and the projector, and one for thesecond camera and projector. Besides these calculations, additionalcalculations are performed to determine the correspondence betweenprojected and imaged scanners spots based on epipolar constraints.

The color camera 2218 may be used to assist in registering multiple 3Dscans obtained by the scanner 2210 by identifying common target featuresand adjusting the pose of the multiple 3D scans to obtain the bestmatch, for example by using mathematical optimization methods such asleast-squares methods.

Area scanners are also available that arrange the two cameras andprojector in a line rather than in a triangle. Usually this arrangementis used as a way of eliminating many of the “shadows” that sometimesoccur when a single scanner is used to view a 3D object. In one method,a single triangulation calculation is performed between the two camerasor between the projector and one of the cameras. In an embodiment, allthree triangulation calculations are performed to improve accuracy.However, with the two cameras and the projector arranged in a straightline, it is desired to project a coded pattern from a handheld scannerto determine the correspondence between projected and imaged scannerspots since epipolar constraints may not be used to determine thecorrespondence directly.

This triangular arrangement of the scanner 2210 of FIG. 22 providesadditional information beyond that available for two cameras and aprojector arranged in a straight line. The additional information may beunderstood in reference to FIG. 23A, which explains the concept ofepipolar constraints, and FIG. 23B that explains how epipolarconstraints are advantageously applied to the triangular arrangement ofthe 3D imager 2210. In FIG. 23A, a 3D triangulation instrument 1240includes a Device 1 and a Device 2 on the left and right sides of FIG.23A, respectively. Device 1 and Device 2 may be two cameras or Device 1and Device 2 may be one camera and one projector. Each of the twodevices, whether a camera or a projector, has a perspective center, O₁and O₂, and a representative plane, 1230 or 1210. The perspectivecenters are separated by a baseline distance B, which is the length ofthe line 1202. The perspective centers O₁, O₂ are points through whichrays of light may be considered to travel, either to or from a point onan object. These rays of light either emerge from an illuminatedprojector pattern or impinge on a photosensitive array. The illuminatedprojector pattern or image plane of the photosensitive array are movedto the other side of the perspective center as this placement issymmetrical and equivalent to the actual projector plane or image planeand simplifies the analysis described herein below. This placement ofthe reference planes 1230, 1210 is applied in FIG. 23A, which shows thereference planes 1230, 1210 between the object point and the perspectivecenters O₁, O₂.

In FIG. 23A, for the reference plane 1230 angled toward the perspectivecenter O₂ and the reference plane 1210 angled toward the perspectivecenter O₁, a line 1202 drawn between the perspective centers O₁ and O₂crosses the planes 1230 and 1210 at the epipole points E₁, E₂,respectively. Consider a point U_(D) on the plane 1230. If Device 1 is acamera, it is known that an object point that produces the point U_(D)on the image lies on the line 1238. The object point might be, forexample, one of the points V_(A), V_(B), V_(C), or V_(D). These fourobject points correspond to the points W_(A), W_(B), W_(C), W_(D),respectively, on the reference plane 1210 of Device 2. This is truewhether Device 2 is a camera or a projector. It should also beappreciated that the four points lie on a straight line 1212 in theplane 1210. This line, which is the line of intersection of thereference plane 1210 with the plane of O₁-O₂-U_(D), is referred to asthe epipolar line 1212. It follows that any epipolar line on thereference plane 1210 passes through the epipole E₂. Just as there is anepipolar line on the reference plane of Device 2 for any point on thereference plane of Device 1, there is also an epipolar line 1234 on thereference plane of Device 1 for any point on the reference plane ofDevice 2.

FIG. 23B illustrates the epipolar relationships for a 3D imager 1290corresponding to 3D imager 2210 of FIG. 22 in which two cameras and oneprojector are arranged in a triangular pattern. In general, the Device1, Device 2, and Device 3 may be any combination of cameras andprojectors as long as at least one of the devices is a camera. Each ofthe three devices 1291, 1292, 1293 has a perspective center O₁, O₂, O₃,respectively, and a reference plane 1260, 1270, and 1280, respectively.Each pair of devices has a pair of epipoles. Device 1 and Device 2 haveepipoles E₁₂, E₂₁ on the planes 1260, 1270, respectively. Device 1 andDevice 3 have epipoles E₁₃, E₃₁, respectively on the planes 1260, 1280,respectively. Device 2 and Device 3 have epipoles E₂₃, E₃₂ on the planes1270, 1280, respectively. In other words, each reference plane includestwo epipoles. The reference plane for Device 1 includes epipoles E₁₂ andE₁₃. The reference plane for Device 2 includes epipoles E₂₁ and E₂₃. Thereference plane for Device 3 includes epipoles E₃₁ and E₃₂.

Consider the situation of FIG. 23B in which device 3 is a projector,Device 1 is a first camera, and Device 2 is a second camera. Supposethat a projection point P₃, a first image point P₁, and a second imagepoint P₂ are obtained in a measurement. These results can be checked forconsistency in the following way.

To check the consistency of the image point P₁, intersect the planeP₃-E₃₁-E₁₃ with the reference plane 1260 to obtain the epipolar line1264. Intersect the plane P₂-E₂₁-E₁₂ to obtain the epipolar line 1262.If the image point P₁ has been determined consistently, the observedimage point P₁ will lie on the intersection of the calculated epipolarlines 1262 and 1264.

To check the consistency of the image point P₂, intersect the planeP₃-E₃₂-E₂₃ with the reference plane 1270 to obtain the epipolar line1274. Intersect the plane P₁-E₁₂-E₂₁ to obtain the epipolar line 1272.If the image point P₂ has been determined consistently, the observedimage point P₂ will lie on the intersection of the calculated epipolarlines 1272 and 1274.

To check the consistency of the projection point P₃, intersect the planeP₂-E₂₃-E₃₂ with the reference plane 1280 to obtain the epipolar line1284. Intersect the plane P₁-E₁₃-E₃₁ to obtain the epipolar line 1282.If the projection point P₃ has been determined consistently, theprojection point P₃ will lie on the intersection of the calculatedepipolar lines 1282 and 1284.

The redundancy of information provided by using a 3D imager 2210 havinga triangular arrangement of projector and cameras may be used to reducemeasurement time, to identify errors, and to automatically updatecompensation/calibration parameters.

In an embodiment, perspective centers of the cameras 2214, 2216 and theprojector 2212 lie in a first plane of the 3D imager 2210. The cameras2214, 2216, and the projector 2212 further have corresponding opticalaxes, each of the optical axes passing through the perspective center,each of the optical axes being generally along a direction perpendicularto the lens system of the camera or projector. In an embodiment, thefirst plane that includes the three perspective centers does not furthercontain the optical axes of the either camera 2214, 2216 or the opticalaxis of the projector 2212. In other words, the triangulation pattern ofthe scanner 2210 conforms to the illustration of FIG. 22 rather thanplacing the three perspective centers in a plane perpendicular to theplane of the front view of FIG. 22.

In an embodiment, there are three baseline distances 2220A, 2220B, and2220C between pairs of the perspective centers of the two cameras 2214,2216 and the projector 2212. Although a single baseline distance issufficient to determine 3D coordinates of an object with the scanner2210, it is advantageous to perform the calculation using all threebaseline distances 2220A, 2220B, and 2220C.

In an embodiment, epipolar constraints, as described herein above withrespect to FIG. 23B, are used to determine 3D coordinates of points onan object. Although it is not always necessary to use epipolarconstraints in the determination of 3D distances, there are advantagesin using the epipolar constraints as described herein above.

In an embodiment, 3D imager 2210 may include a display (not shown),which may be integrated with a touchscreen. Such a display may providereal-time or near real-time scanning information. It may also providemessages and enable a user to enter instructions through an userinterface tied to the touchscreen. In a further embodiment, the 3Dimager may include a replaceable battery, a controller, and a wirelesscommunication system. In an embodiment, the color camera 2218 mayfurther be used to attach colors to the 3D points obtained with the 3Dimager 2210.

The scanner 2210 includes a detachable coupler 426A by which it attachesto a mating connector 426C on an AACMM 100 or on a connector 426B on anassembly such as the six-DOF tracker target assembly 1910, as shown inFIG. 22. It may alternatively attach to the camera assembly 1850 or thesix-DOF light point target assembly 2000. The scanner 2210 may also havea removable handle that enables it to sit flat. This may be useful forexample in an assembly line application such as an application involvinga conveyor belt.

In accordance with an embodiment, a device for measuringthree-dimensional (3D) coordinates of an object having a surfaceincludes: a processor; a triangulation scanner including a projector, ascanner camera, and a scanner connector, the projector configured toproject a scanner pattern onto the object surface, the scanner cameraconfigured to form an image of the scanner pattern and to send anelectrical scanner signal to the processor in response, there being ascanner baseline distance between the scanner camera and the projector,the scanner connector configured to detachably couple to a connector ofan articulated arm coordinate measurement machine (AACMM); and a cameraassembly including a first assembly camera and a camera assemblyconnector, the first assembly camera configured to form a first image ofthe object surface and to send a first electrical assembly signal to theprocessor in response, the camera assembly connector configured todetachably couple to the scanner connector, wherein the processor isconfigured to determine the 3D coordinates of the object surface whetherthe triangulation scanner is coupled to or uncoupled from the AACMM, thedetermining based at least in part on the scanner pattern, the firstelectrical scanner signal, and the scanner baseline distance. In afurther embodiment, the device of is configured to determine the 3Dcoordinates of the object surface further based on the first electricalassembly signal when the camera assembly connector is coupled to thescanner connector. In accordance with a further embodiment, the cameraassembly further includes a second assembly camera, the second assemblycamera being configured to form a second image of the object surface andto send a second electrical assembly signal to the processor inresponse, there being an assembly baseline distance between the firstassembly camera and the second assembly camera, the processor beingconfigured to determine the 3D coordinates of the object surface furtherbased on the second electrical assembly signal and the assembly baselinedistance. In an embodiment, the triangulation scanner is a laser lineprobe, with the projector is configured to project a line of light. Inan embodiment, the triangulation scanner is an area scanner, with theprojector configured to project light to cover an area on the objectsurface. In an embodiment, the first assembly camera further includes afirst assembly light source proximate the first assembly camera, thefirst assembly light source configured to illuminate a reflective markeron the object surface or proximate the object surface. In an embodiment,the device further comprises a battery. In an embodiment, the devicefurther includes a color camera configured to produce a color image, thecolor camera configured to produce an electrical signal of the colorimage, the processor being configured to add color to the 3D coordinatesof the object surface based at least in part on the electrical signal ofthe color image. In an embodiment, the device further includes adisplay, which may further include a touch screen.

In accordance with an embodiment, a method for measuringthree-dimensional (3D) coordinates includes: providing an object, aprocessor, a triangulation scanner, a camera assembly, and a mark, theobject having a surface, the triangulation scanner including aprojector, a scanner camera, and a scanner connector, the cameraassembly including a first assembly camera and a camera assemblyconnector, the camera assembly connector configured to detachably coupleto the scanner connector, the mark being on the object or proximate theobject; and connecting the scanner connector to the camera assemblyconnector. In a first instance of the embodiment, the embodimentincludes: projecting with the projector a first light onto the objectsurface; forming with the scanner camera an image of the first light andsending a first electrical scan signal to the processor in response;forming with the first assembly camera a first image of the mark andsending a first electrical mark signal to the processor in response. Ina second instance of the embodiment, the embodiment includes: projectingwith the projector a second light onto the object surface; forming withthe scanner camera an image of the second light and sending a secondelectrical scan signal to the processor in response; forming with thefirst assembly camera a second image of the mark and sending a secondelectrical mark signal in response. In addition, the embodiment furtherincludes determining with the processor the 3D coordinates based atleast in part on the first light, the second light, the first electricalscan signal, the second electrical scan signal, the first electricalmark signal, and the second electrical mark signal; and storing the 3Dcoordinates. In a further embodiment, the triangulation scanner is alaser line probe. In a further embodiment, the triangulation scanner isan area scanner. In a further embodiment, the mark is a natural featureof the object. In a further embodiment, the mark is a light emittingdiode (LED) place on the object or in proximity to the object. In afurther embodiment, the mark is a reflective target. In a furtherembodiment, the camera assembly further includes a light source. In afurther embodiment, the mark is a reflective target illuminated by thelight source on the camera assembly. A further embodiment includesproviding an external projector, the external projector separate fromthe triangulation scanner and the camera assembly. In a furtherembodiment, the mark is a spot of light projected by the externalprojector. A further embodiment includes providing three marks. In afurther embodiment, the first image includes the three marks and thesecond image includes the three marks. In a further embodiment, thecamera assembly further includes a second assembly camera. In a furtherembodiment includes: in the first instance, forming with the secondassembly camera a third image of the mark and sending a third electricalmark signal to the processor in response, and, in the second instance,forming with the second assembly camera a fourth image of the mark andsending a fourth electrical mark signal to the processor in response. Ina further embodiment, the processor determines 3D coordinates furtherbased on the third electrical mark signal and the fourth electrical marksignal.

In accordance with an embodiment, a system for measuringthree-dimensional (3D) coordinates of an object surface includes: aprocessor; a target device including a triangulation scanner and a sixdegree-of-freedom (six-DOF) target assembly, the triangulation scannerincluding a projector, a scanner camera, and a scanner connector, theprojector configured to project a scanner pattern onto the objectsurface, the scanner camera configured to form an image of the scannerpattern and to send an electrical scanner signal to the processor inresponse, the six-DOF target assembly including a collection of lightpoints and an assembly connector configured to detachably couple to thescanner connector; a camera bar device including a first camera and asecond camera separated by a camera-bar baseline distance, the firstcamera and the second camera fixed in space, the first camera configuredto form a first light point image of the collection of light points andto send a first electrical light point signal to the processor inresponse, the second camera configured to form a second light pointimage of the collection of light points and to send a second electricallight point signal to the processor in response, wherein the processoris configured to determine the 3D coordinates of the object surfacebased at least in part on the scanner pattern, the electrical scannersignal, the first electrical light point signal, the second electricallight point signal, and the camera-bar baseline distance. In accordancewith a further embodiment, the processor is further configured todetermine the 3D coordinates of the object surface based at least inpart on a scanner baseline distance between the scanner camera and theprojector. In a further embodiment, the triangulation scanner is a laserline probe configured to project a line of light. In a furtherembodiment, the triangulation scanner is an area scanner configured toproject light to cover an area on the object surface. In a furtherembodiment, the six-DOF target assembly further includes a tactile probeconfigured to measure 3D coordinates of points on the object surface. Ina further embodiment, the scanner connector is further configured todetachably couple to a first connector of an articulated arm coordinatemeasurement machine (CMM). In a further embodiment, the scanner furthercomprises a battery. In a further embodiment, the system furthercomprises a color camera configured to produce a color image, the colorcamera configured to produce an electrical signal of the color image,the processor being configured to add color to the 3D coordinates of theobject surface based at least in part on the electrical signal of thecolor image. In a further embodiment, the system further comprises adisplay, which may include a touch screen.

In an embodiment, a method for measuring three-dimensional (3D)coordinates of an object surface includes: providing a processor;providing a target device including a triangulation scanner and a sixdegree-of-freedom (six-DOF) target assembly, the triangulation scannerincluding a projector, a scanner camera, and a scanner connector, thesix-DOF target assembly including a collection of light points and anassembly connector configured to detachably couple to the scannerconnector; providing a camera bar device including a first camera and asecond camera separated by a camera-bar baseline distance, the firstcamera and the second camera fixed in space; connecting the scannerconnector to the assembly connector. In a first instance of theembodiment, the embodiment includes: projecting with the projector afirst light onto the object surface; forming with the scanner camera animage of the first light and sending a first electrical scan signal tothe processor in response; forming with the first camera a first lightpoint image of the collection of light points and sending a firstelectrical light point signal to the processor in response; forming withthe second camera a second light point image of the collection of lightpoints and sending a second electrical light point signal to theprocessor in response; determining by the camera bar device incooperation with the processor and the six-DOF target assembly firstvalues for six degrees of freedom of the triangulation scanner;determining with the processor the 3D coordinates of the object surfacebased at least in part on the first light, the first electrical scansignal, the first electrical light point signal, and the secondelectrical light point signal; and storing the 3D coordinates of theobject surface. In a further embodiment, in a second instance, theembodiment further includes: projecting with the projector a secondlight onto the object surface; forming with the scanner camera an imageof the second light and sending a second electrical scan signal to theprocessor in response; forming with the first camera a third light pointimage of the collection of light points and sending a third electricallight point signal to the processor in response; forming with the secondcamera a fourth light point image of the collection of light points andsending a fourth electrical light point signal to the processor inresponse; and determining with the processor the 3D coordinates of theobject surface further based on the second light, the second electricalscan signal, the third electrical light point signal, and the fourthelectrical light point signal. In a further embodiment, thetriangulation scanner is a laser line probe that projects a line oflight. In a further embodiment, the triangulation scanner is an areascanner that projects light over an area. In a further embodiment, theprocessor is further configured to determine the 3D coordinates of theobject surface based at least in part on a scanner baseline distancebetween the scanner camera and the projector. In a further embodiment,the assembly further includes a tactile probe.

In an embodiment, a method for measuring three-dimensional (3D)coordinates of a tactile probe includes: providing a processor;providing a target device including a triangulation scanner and a sixdegree-of-freedom (six-DOF) target assembly, the triangulation scannerincluding a scanner connector, the six-DOF target assembly including acollection of light points, the tactile probe, and an assembly connectorconfigured to detachably coupled to the scanner connector; providing acamera bar device including a first camera and a second camera separatedby a camera-bar baseline distance, the first camera and the secondcamera fixed in space; connecting the scanner connector to the assemblyconnector; forming with the first camera a first light point image ofthe collection of light points and sending a first electrical lightpoint signal to the processor in response; forming with the secondcamera a second light point image of the collection of light points andsending a second electrical light point signal to the processor inresponse; and determining with the processor the 3D coordinates of theobject surface based at least in part on first electrical light pointsignal, and the second electrical light point signal, and the car-barbaseline distance.

In an embodiment, a device for measuring three-dimensional (3D)coordinates of an object having a surface includes: a processor; atriangulation scanner including a projector, a scanner camera, and ascanner connector, the projector configured to project a scanner patternonto the object surface, the scanner camera configured to form an imageof the scanner pattern and to send an electrical scanner signal to theprocessor in response; and a six degree-of-freedom (six-DOF) trackertarget assembly including a retroreflector and an assembly connector,the retroreflector configured to return light received from a lasertracker, the six-DOF tracker target assembly further configured tocooperate with the laser tracker and the processor to determine sixdegrees of freedom of the triangulation scanner, the assembly connectorconfigured to detachably couple to the scanner connector, wherein theprocessor is configured to determine the 3D coordinates of the objectsurface based at least in part on the scanner pattern, the electricalscanner signal, and the six degrees of freedom of the triangulationscanner. In a further embodiment, the processor is further configured todetermine the 3D coordinates of the object surface based at least inpart on a scanner baseline distance between the scanner camera and theprojector. In a further embodiment, the triangulation scanner is a laserline probe having a projector configured to project a line of light. Ina further embodiment, the triangulation scanner is an area scannerhaving a projector configured to project a light to cover an area. In afurther embodiment, the six-DOF tracker target assembly further includesa tactile probe configured to measure 3D coordinates of points on theobject surface. In a further embodiment, each of the plurality ofsix-DOF tracker target assemblies are measurable from a differentdirection by the laser tracker. In a further embodiment, the scannerconnector is further configured to detachably couple to a firstconnector of an articulated arm coordinate measurement machine (CMM).

In an embodiment, a method for measuring three-dimensional (3D)coordinates of an object surface includes: providing a processor, atriangulation scanner, and a six degree-of-freedom (six-DOF) trackertarget assembly, the triangulation scanner including a projector, ascanner camera, and a scanner connector, the six-DOF tracker targetassembly including a retroreflector and an assembly connector configuredto detachably couple to the scanner connector; connecting the scannerconnector to the assembly connector. In a first instance of theembodiment, the embodiment further includes: projecting with theprojector a first light onto the object surface; forming with thescanner camera an image of the first light and sending a firstelectrical scan signal to the processor in response; determining by thelaser tracker in cooperation with the processor and the six-DOF trackertarget assembly a first set of values for six degrees of freedom of thetriangulation scanner; determining with the processor the 3D coordinatesof the object surface based at least in part on the first light, thefirst electrical scan signal, and the first values for six degrees offreedom of the triangulation scanner; and storing the 3D coordinates ofthe object surface. In a further embodiment, in a second instance, theembodiment further includes projecting with the projector a second lightonto the object surface; forming with the scanner camera an image of thesecond light and sending a second electrical scan signal to theprocessor in response; determining by the laser tracker in cooperationwith the processor a second set of values for six degrees of freedom ofthe triangulation scanner; determining with the processor additional 3Dcoordinates of the object surface based at least in part on the secondlight, the second electrical scan signal, and the second values for sixdegrees of freedom of the triangulation scanner, and storing theadditional 3D coordinates of the object surface. In a furtherembodiment, the triangulation scanner is a laser line probe. In afurther embodiment, the triangulation scanner is an area scanner. In afurther embodiment, the processor is further configured to determine the3D coordinates of the object surface based at least in part on a scannerbaseline distance between the scanner camera and the projector. In afurther embodiment, the assembly further includes a tactile probe. In afurther embodiment, the method further includes: determining by thelaser tracker in cooperation with the processor and the six-DOF trackertarget assembly a third set of values for six degrees of freedom of thetriangulation scanner; and determining by the processor the 3Dcoordinates of the tactile probe based at least in part on the third setof values. In a further embodiment, the method further includes sendinga beam of light from the laser tracker to the retroreflector, receivinga portion of reflected light in a distance meter of the laser tracker,and determining a distance from the laser tracker to the retroreflectorwith the distance meter; and measuring with the tracker a first angleand a second angle of the beam of light. In a further embodiment, thefirst set of values is further based on the distance from the lasertracker to the retroreflector, the first angle, and the second angle.

While the invention has been described with reference to exampleembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims. Moreover, the use of the terms first, second, etc. do not denoteany order or importance, but rather the terms first, second, etc. areused to distinguish one element from another. Furthermore, the use ofthe terms a, an, etc. do not denote a limitation of quantity, but ratherdenote the presence of at least one of the referenced item.

What is claimed is:
 1. A device for measuring three-dimensional (3D)coordinates of an object surface comprising: a processor; and atriangulation scanner including a projector, a first scanner camera, asecond scanner camera, and a scanner connector, the scanner connectorconfigured to detachably couple to an arm connector of an articulatedarm coordinate measurement machine (AACMM), the projector configured toproject a scanner pattern onto the object surface, the projector havinga projector perspective center and a projector optical axis, the firstscanner camera configured to form a first image of the scanner patternand to send a first electrical scanner signal to the processor inresponse, the first scanner camera having a first-camera perspectivecenter and a first-camera optical axis, the second scanner cameraconfigured to form a second image of the scanner pattern and to send asecond electrical scanner signal to the processor in response, thesecond camera having a second-camera perspective center and asecond-camera optical axis, the projector perspective center, thefirst-camera perspective center, and the second-camera perspectivecenter being arranged in a triangular pattern on a first plane, thefirst plane not including the projector optical axis, the first-cameraoptical axis, or the second-camera optical axis, wherein the processoris configured to determine the 3D coordinates of the object surfacewhether the triangulation scanner is coupled to or uncoupled from theAACMM, the determining based at least in part on the scanner pattern,the first electrical scanner signal, and the second electrical scannersignal.
 2. The device of claim 1 wherein the processor is furtherconfigured to determine the 3D coordinates of the object surface basedon a first baseline distance from the first-camera perspective center tothe projector perspective center, a second baseline distance from thesecond-camera perspective center to the projector perspective center,and a third baseline distance from the first-camera perspective centerto the second-camera perspective center.
 3. The device of claim 1wherein the triangulation scanner includes a first set of epipolarconstraints between the first camera and the projector, a second set ofepipolar constraints between the second camera and the projector, and athird set of epipolar constraints between the first camera and thesecond camera, the processor being configured to determine the 3Dcoordinates of the object surface further based on the first set ofepipolar constraints, the second set of epipolar constraints, and thethird set of epipolar constraints.
 4. The device of claim 1 wherein theprojector is configured to produce the scanner pattern by sending lightthrough a diffractive optical element.
 5. The device of claim 1 whereinthe projector comprises a scanner light source and a scanner digitalmicromirror device (DMD), the scanner light source and the scanner DMDbeing configured to produce the scanner pattern.
 6. The device of claim1 further comprising: a six degree-of-freedom (six-DOF) tracker targetassembly including a retroreflector and an assembly connector, theretroreflector configured to return light received from a laser tracker,the six-DOF tracker target assembly further configured to cooperate withthe laser tracker and the processor to determine six degrees of freedomof the triangulation scanner, the assembly connector configured todetachably couple to the scanner connector, the processor beingconfigured to determine the 3D coordinates of the object surface furtherbased on the determined six degrees of freedom of the triangulationscanner.
 7. The device of claim 1 further comprising: a sixdegree-of-freedom (six-DOF) target assembly including a collection oflight points and an assembly connector configured to detachably coupleto the scanner connector, wherein the six-DOF target assembly isconfigured to cooperate with a camera bar device, the camera bar deviceincluding a first camera and a second camera separated by a camera-barbaseline distance, the first camera and the second camera fixed inspace, the first camera configured to form a first light point image ofthe collection of light points and to send a first electrical lightpoint signal to the processor in response, the second camera configuredto form a second light point image of the collection of light points andto send a second electrical light point signal to the processor inresponse, the processor being configured to determine the 3D coordinatesof the object surface further based on the first electrical light pointsignal, the second electrical light point signal, and the camera-barbaseline distance.
 8. The device of claim 1 wherein the triangulationscanner further comprises a battery.
 9. The device of claim 1 furthercomprising a display.
 10. The device of claim 9 wherein the displayincludes a touch screen.
 11. The device of claim 1 further comprises acolor camera configured to produce a color image, the color cameraconfigured to produce an electrical signal of the color image, theprocessor being configured to add color to the 3D coordinates of theobject surface based at least in part on the electrical signal of thecolor image.
 12. The device of claim 1 wherein the device furthercomprises a battery.
 13. The device of claim 1 further comprising adisplay.
 14. The device of claim 13 wherein the display includes a touchscreen.
 15. A device for measuring three-dimensional (3D) coordinates ofan object surface comprising: a processor; and a triangulation scannerincluding a projector, a scanner camera, a detachable handle, and ascanner connector, the projector configured to project a scanner patternonto the object surface, the scanner camera configured to form an imageof the scanner pattern and to send an electrical scanner signal to theprocessor in response, the scanner connector configured to detachablycouple to a connector of an articulated arm coordinate measurementmachine (AACMM), the processor being configured to determine the 3Dcoordinates of the object surface whether the triangulation scanner iscoupled to on uncoupled from the AACMM, the determining based at leastin part on the scanner pattern and on the electrical scanner signal,wherein the triangulation scanner is configured to sit flat on itsbottom after removal of the detachable handle.
 16. The device of claim15 further comprising a six degree-of-freedom (six-DOF) tracker targetassembly including a retroreflector and an assembly connector, theretroreflector configured to return light received from a laser tracker,the six-DOF tracker target assembly further configured to cooperate withthe laser tracker and the processor to determine six degrees of freedomof the triangulation scanner, the assembly connector configured todetachably couple to the scanner connector, the processor beingconfigured to determine the 3D coordinates of the object surface furtherbased on the determined six degrees of freedom of the triangulationscanner.
 17. The device of claim 15 further comprising: a sixdegree-of-freedom (six-DOF) target assembly including a collection oflight points and an assembly connector configured to detachably coupleto the scanner connector, wherein the six-DOF target assembly isconfigured to cooperate with a camera bar device, the camera bar deviceincluding a first camera and a second camera separated by a camera-barbaseline distance, the first camera and the second camera fixed inspace, the first camera configured to form a first light point image ofthe collection of light points and to send a first electrical lightpoint signal to the processor in response, the second camera configuredto form a second light point image of the collection of light points andto send a second electrical light point signal to the processor inresponse, and wherein the processor is configured to determine the 3Dcoordinates of the object surface further based on the first electricallight point signal, the second electrical light point signal, and thecamera-bar baseline distance.
 18. The device of claim 15 furthercomprising a camera assembly including a first assembly camera and acamera assembly connector, the first assembly camera configured to forma first image of the object surface and to send a first electricalassembly signal to the processor in response, the camera assemblyconnector configured to detachably couple to the scanner connector, theprocessor being configured to determine the 3D coordinates of the objectsurface further based on the first electrical assembly signal.
 19. Thedevice of claim 18 wherein the camera assembly further includes a secondassembly camera, the second assembly camera configured to form a secondimage of the object surface and to send a second electrical assemblysignal to the processor in response, there being an assembly baselinedistance from the first assembly camera to the second assembly camera,the processor being configured to determine the 3D coordinates of theobject surface further based on the second electrical assembly signaland the assembly baseline distance.
 20. The device of claim 15 whereinthe triangulation scanner is a laser line probe.
 21. The device of claim20 wherein the projector is configured to project a line of light. 22.The device of claim 15 wherein the triangulation scanner is an areascanner.
 23. The device of claim 22 wherein the projector is configuredto project light to cover an area on the object surface.
 24. The deviceof claim 15 wherein the device is further configured to attach to areal-time bus selected from the group consisting of: EtherCAT, SERCOSIII, PROFINET, POWERLINK, and EtherNet/IP.
 25. The device of claim 15wherein the device further comprises a battery.
 26. The device of claim15 wherein the triangulation scanner further comprises a color cameraconfigured to produce a color image, the color camera configured toproduce an electrical signal of the color image, the processor beingconfigured to add color to the 3D coordinates of the object surfacebased at least in part on the electrical signal of the color image. 27.The device of claim 15 further comprising a display.
 28. The device ofclaim 27 wherein the display includes a touch screen.